Biofouling remains a significant challenge in water treatment fields, leading to a decline in the hydraulic performance, increased operational costs, and potential health risks. Previous biofouling control strategies primarily focused on the removal of particulates and microorganisms, often neglecting the role of extracellular proteins. Using a reclaimed water distribution system as an example, this study proposes a strategy to inhibit biofouling formation by utilizing urea, a reported protein denaturant with fertilizer functionality. Results indicated that urea significantly slowed the accumulation of biofouling, leading to a 16.4-49.4 % decrease in biofouling weight, an 18.6-55.3 % decrease in extracellular protein content, and a 25.9-45.3 % reduction in extracellular polymer substance (EPS) content. Urea mitigated biofouling through two mechanisms: (1) disrupting protein structures, which convert tightly bound EPS to loosely bound EPS, and (2) downregulating biofilm-forming signaling proteins, thereby inhibiting biofouling formation. In the process, proteins, polysaccharides, and microorganisms exhibited clear mutual promotion relationships. Additionally, urea weakened microbial symbiotic interactions by affecting protein signaling molecules, inhibiting microbial growth and polysaccharide metabolism. The research confirms that denaturing extracellular proteins to mitigate biofouling is a feasible and efficient approach. The findings aim to provide valuable insights for the development of sustainable and effective biofouling cleaning strategies.

Biofilm infections represent the greatest risk associated with medical devices and implants, constituting 65 %-70 % of all device associated infections. Efforts to develop antimicrobial technologies for biomedical applications aim to reduce infection rates, antibiotic use, and the induction of antimicrobial resistance. However, standard laboratory test conditions often overestimate efficacy, highlighting the need for experimental designs that simulate real-world settings. To this end, we evaluated four commercially available antimicrobial materials containing silver (AG1, AG2, AG3) or zinc (ZN1) to assess their ability to mitigate microbial proliferation in for longer duration or multi-use medical devices. The materials' homogeneity and surface topography were characterized through Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM). Antimicrobial efficacy was tested using a modified ISO 22196 protocol under clinically relevant conditions and a dry contact test developed to mimic in-use conditions for many extracorporeal medical devices. Results revealed homogeneous elemental distributions in AG1, AG2, and ZN1, and heterogeneous clusters for AG3. Surface roughness was highest for AG2 (170.1 nm), followed by TPE control (155.3 nm), ZN1 (83.51 nm) and silicone control (66.74 nm). All test materials demonstrated antimicrobial efficacies against S. aureus and E. coli, but not against C. albicans. In the dry contact assay, only AG2 proved effective against E. coli, and P. aeruginosa, underlining the role of humidity in antimicrobial action. Results were further corroborated by measurement of ion release by the materials at various temperatures, revealing greater release at higher temperatures. These outcomes emphasize the importance of testing antimicrobial materials under in use conditions to minimize discrepancies between laboratory results and clinical outcomes. Our findings provide a valuable framework for testing and integrating these materials into next-generation multi-use medical devices.

Corrosion research, spanning over 150 years, remains critically important, particularly for addressing marine microbially induced corrosion on steel, which causes significant economic losses and safety risks. This study proposes a biomineralization method using marine urease-producing bacteria to protect steel. Urease-producing bacteria were enriched to promote biomineralization, and a seawater corrosion experiment was conducted to evaluate its efficacy. Results showed that biomineralization significantly reduced corrosion rates, especially with yeast extract enrichment, and decreased the abundance of sulfate-reducing bacteria and sulfur-oxidizing bacteria in biofilms. Functional gene analysis identified Thioalkalivibrio as a key indicator of sulfate reduction. The findings demonstrated that the formed biomineralized film acted as a protective layer to isolate the steel from the corrosive seawater, which contributed to the advancement of novel techniques for corrosion inhibition of marine steel to achieve long-term sustainability for ships and engineering structures.

Antibiotic resistance in foodborne bacteria poses a substantial global health challenge. Reports indicate that antibiotic overuse in middle-class and low-income countries is a significant factor in the ever-increasing resistance. Resistance mechanisms have developed through enzymatic hydrolysis, reduced membrane permeability, efflux pumps, and target site mutations. Preventive measures like proper hygiene and safe food preparation, vaccination, antibiotic stewardship and surveillance, implementing infection prevention and control (IPC) measures, good agricultural practices, and investigating novel approaches like CRISPR, NGS, nanotechnology, and bacteriophages may be employed to address this challenge. Naturally occurring preservatives (e.g., nisin) are alternatives to antibiotics for food preservation. Prebiotics, probiotics, nanobiotics, phage treatment, and antimicrobial peptides are also substitutes for antibiotics. Furthermore, plant-derived compounds, such as essential oils and plant extracts, are promising substitutes for antibiotics in animal production. This review focuses on the mechanisms of underlying antibiotic resistance in foodborne pathogens, necessary preventive measures, and the challenges associated.

Created using BioRender https://www.biorender.com/.

The widespread prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has caused serious challenges to clinical treatment. This study was designed to explore effective targets for MRSA prevention and control. The key virulence regulator was screened through the correlation analysis between virulence and various regulatory factors in the main clinical epidemic MRSA. The potential key factors were inactivated to further evaluate the inhibitory effect on the virulence of MRSA standard strain S. aureus ATCC43300 and its influence on drug resistance and biofilm formation. Enterobacterial repetitive intergenic consensus-PCR was used to analyze the clinical epidemic genotypes of MRSA. The virulence of MRSA was evaluated mainly by measuring its adhesion and invasion ability to A549 cells, the lethality to Galleria mellonella larvae, and the transcription level of related genes. The biofilm formation was assessed by crystal violet staining on polystyrene microplates. The results showed that most virulence factors of clinical representative MRSA strain were significantly positively correlated with RsbUVW system. After knocking out the rsbV gene, a key component of the rsbUVW system, the virulence of S. aureus ATCC43300 was significantly reduced (P < 0.05), as indicated by a significant decrease in lethality against G. mellonella larvae and invasion against A549 cells, and a significant decrease in the expression of immune escape related virulence factors polysaccharide intercellular adhesin (PIA) and staphyloxanthin. The biomass and stability of protein-dependent biofilm by S. aureus ATCC43300 were significantly increased. This study will provide useful information for the effective prevention and control of MRSA.

The genus Leptospira comprises unique atypical spirochete bacteria that includes the etiological agent of leptospirosis, a globally important zoonosis. Biofilms are microecosystems composed of microorganisms embedded in a self-produced matrix that offers protection against hostile factors. Leptospires form biofilms in vitro, in situ in rice fields and unsanitary urban areas, and in vivo while colonizing rodent kidneys. The complex three-dimensional biofilm matrix includes secreted polymeric substances such as proteins, extracellular DNA (eDNA), and saccharides. The genus Leptospira comprises pathogenic and saprophytic species with the saprophytic L. biflexa being commonly used as a model organism for the genus. In this study, the growth and formation of biofilms by L. biflexa was investigated not just at 29 °C, but at 37 °C/5 % CO2, a temperature similar to that encountered during host infection. Planktonic free-living L. biflexa grow in HAN media at both 29 °C and 37 °C/5 % CO2, but cells grown at 37 °C/5 % CO2 are longer (18.52 μm ± 3.39) compared to those at 29 °C (13.93 μm ± 2.84). Biofilms formed at 37 °C/5 % CO2 had more biomass compared to 29 °C, as determined by crystal violet staining. Confocal microscopy determined that the protein content within the biofilm matrix was more prominent than double-stranded DNA, and featured a distinct layer attached to the solid substrate. Additionally, the model enabled effective protein extraction for proteomic comparison across different biofilm phenotypes. Results highlight an important role for proteins in biofilm matrix structure by leptospires and the identification of their specific protein components holds promise for strategies to mitigate biofilm formation.

Vibrio cholerae pathogens cause cholera, an acute diarrheal disease resulting in significant morbidity and mortality worldwide. Biofilms in vibrios enhance their survival in natural ecosystems and facilitate transmission during cholera outbreaks. Critical components of the biofilm matrix include the Vibrio polysaccharides produced by the vps-1 and vps-2 gene clusters and the biofilm matrix proteins encoded in the rbm gene cluster, together comprising the biofilm matrix cluster. However, the biofilm matrix clusters and their evolutionary patterns in other Vibrio species remain underexplored. In this study, we systematically investigated the distribution, diversity, and evolution of biofilm matrix clusters and proteins across the Vibrio genus. Our findings reveal that these gene clusters are sporadically distributed throughout the genus, even appearing in species phylogenetically distant from Vibrio cholerae. Evolutionary analysis of the major biofilm matrix proteins RbmC and Bap1 shows that they are structurally and sequentially related, having undergone structural domain and modular alterations. Additionally, a novel loop-less Bap1 variant was identified, predominantly represented in two phylogenetically distant V. cholerae subspecies clades that share specific gene groups associated with the presence or absence of the protein. Furthermore, our analysis revealed that rbmB, a gene involved in biofilm dispersal, shares a recent common ancestor with Vibriophage tail proteins, suggesting that phages may mimic host functions to evade biofilm-associated defenses. Our study offers a foundational understanding of the diversity and evolution of biofilm matrix clusters in vibrios, laying the groundwork for future biofilm engineering through genetic modification.

Biofilms help vibrios survive in nature and spread cholera. However, the genes that control biofilm formation in vibrios other than Vibrio cholerae are not well understood. In this study, we analyzed the biofilm matrix gene clusters and proteins across diverse Vibrio species to explore their patterns and evolution. We discovered that these genes are spread across different Vibrio species, including those not closely related to V. cholerae. We also found various forms of key biofilm proteins with different structures. Additionally, we identified genes involved in biofilm dispersal that are related to vibriophage genes, highlighting the role of phages in biofilm development. This study not only provides a foundational understanding of biofilm diversity and evolution in vibrios but also leads to new strategies for engineering biofilms through genetic modification, which is crucial for managing cholera outbreaks and improving the environmental resilience of these bacteria.

Fish granulomatous diseases induced by Nocardia seriolae have caused significant economic losses in global aquaculture. Understanding the structural and genetic basis of N. seriolae' s survival and immune evasion strategies is crucial. However, while some aspects of its pathogenicity have been explored, a comprehensive characterization of its ultrastructural features and the associated genetic determinants, especially in direct correlation, has remained incompletely elucidated. In this study, we utilized specialized staining methods to further characterize the pathology of chronic granulomatous inflammation induced by N. seriolae in largemouth bass (Micropterus salmoides). Using scanning electron microscope (SEM) and transmission electron microscope (TEM), we revealed further insights into the morphological (surface structure, cell wall) and intracellular features (mesosomes, ribosomes, lipids) of N. seriolae, alongside diverse division patterns. Through genomic analysis, the gene clusters related to cell wall synthesis and cell division were characterized, including peptidoglycan, arabinogalactan, mycolic acids (MAs) synthesis, and the division and cell wall (DCW) gene cluster, highlighting the conservation and potential functions of these genes in these processes. In conclusion, these findings provide crucial foundational knowledge regarding the ultrastructure and genetic determinants potentially involved in the pathogenicity of N. seriolae. By integrating detailed ultrastructural observations with genomic insights, this study enhances our understanding of its complex biology and aims to strengthen the foundation for the development of prevention, control, and detection methods for fish granulomatous diseases.

Surface-bound biofilms are the predominant microbial life form in the environment and host organisms. Many biofilms survive and thrive under physical stress from liquid flow in streams, fuel lines, blood, and airways. Strategies for biofilm persistence include shear-dependent adhesion (called catch bonding). In some cases, biofilms are physically strengthened by the formation of cross-β bonds between proteins: the same process that generates amyloids. Cross-β bonds have low dissociation rates. In biofilms, they bind cells to substrates, each other, and the biofilm matrix. Most fungal adhesins include amino acid sequences that can form amyloids. Shear flow activates these adhesins by unfolding pseudo-stable protein domains. The unfolding exposes sequence segments that can form cross-β bonds. These segments interact to form high-avidity adhesin patches on the cell surface. Thus, cross-β bonding is a consequence of flow-induced exposure of the cross-β core sequences. Liquid flow leads to both biofilm establishment through catch bonding and biofilm strengthening through amyloid-like bonds. This shear-dependent induction of biofilm establishment and persistence is a model for many microbial systems.IMPORTANCEThe microbes in biofilms persist in many environments, including industrial and pathological settings. These surface-associated communities show high resistance to antibiotics and microbicides. Biofilms also resist scouring by liquid flow. Amyloid-like cross-β bonds allow the establishment, strengthening, and persistence of many biofilms. This discovery opens a window on the novel use of anti-amyloid strategies to control microbes in biofilms.

The misuse and overuse of antibiotics have caused the emergence of antibiotic-resistant bacteria, making bacterial infections more challenging. The increasing prevalence of multidrug-resistant pathogens has driven researchers to explore novel therapeutic strategies. Phototherapy strategies that utilize photo-responsive biomaterials for their antibacterial properties have gained widespread attention due to their capability of precisely controlling bacterial inactivation with minimal side effects. Despite their potential, photodynamic therapies suffer from phototoxicity and low efficiency of photosensitizers, while photothermal therapy risks overheating, which may harm healthy tissues, thus restricting its broader application. Metal organic frameworks (MOFs) have unique physicochemical properties, which provide a promising way to deal with these challenges. MOFs can function as reservoirs, loading and releasing antibacterial agents, such as antibiotics or metal ions, upon light illumination by virtue of their metastable coordination bonds. Their porous structures enable controlled drug release and encapsulation of photosensitizers. Furthermore, MOFs' tunable composition and pore structure allow for the light-triggered generation of heat and reactive oxygen species, enhancing their antibacterial effectiveness. By doping MOFs with functional materials, it is possible to achieve multi-mode antibacterial effects. In this review, we will outline recent advancements of photo-responsive antibacterial MOFs, categorize their underlying mechanisms of action and highlight their prospects in addressing bacterial resistance.

Klebsiella pneumoniae causes both community-acquired and healthcare-associated infections, presenting a major therapeutic challenge to global public health. RstBA is a common two-component regulatory system that controls downstream gene expression in certain Enterobacteriaceae species. However, the role of RstBA in K. pneumoniae infection remains unknown. To determine its function, a wild-type K. pneumoniae strain (ATCC43816) and rstA mutant and complementation strains were constructed. Phenotypic experiments and in vivo animal infection assays demonstrated that deletion of rstA decreased virulence and biofilm formation. RNA sequencing analysis of ATCC43816 and rstA mutant strains was performed to study the regulatory mechanisms, revealing differential expression of genes involved in arginine and proline metabolism, phenylalanine metabolism, and quorum sensing. In addition, the mrkI and the mrkABCDF gene cluster, which regulates and encodes type 3 fimbriae, exhibited lower expression in the absence of rstA, possibly related to decreased virulence and biofilm formation. Quantitative real-time reverse transcription PCR, promoter activity assays, and electrophoretic mobility shift assays were conducted to identify the transcriptional regulation of mrkI and mrkABCDF by rstA. Our findings show that rstA regulates type 3 fimbriae expression by regulating mrkI indirectly and regulating mrkA directly by binding to its promoter. This study provides new insights into the functional importance of RstA in regulating biofilm formation and virulence in K. pneumoniae.IMPORTANCEKlebsiella pneumoniae is an opportunistic pathogen that has become a significant cause of community-acquired and nosocomial infections. The rise of hypervirulent and multi-drug-resistant K. pneumoniae poses a significant threat to public health. The two-component regulatory system is a typical signal-sensing and stress-response system widely distributed in bacteria, playing a critical regulatory role in bacterial infection. Through in vivo and in vitro experiments, we demonstrate that rstA regulates the expression of type 3 fimbriae by regulating mrkI indirectly and mrkA directly, thereby playing an essential role in the virulence and biofilm formation of K. pneumoniae. Understanding the regulatory mechanism of RstA in K. pneumoniae provides a proof-of-concept for identifying new genetic targets for controlling K. pneumoniae infection, which may aid in the development of therapeutic drugs.

Extracellular polymeric substances (EPS) produced by soil bacteria and fungi are crucial for microbial growth and provide many functions for the soil and its microbes. EPS composition may depend on microbial community composition and the soil physical and chemical environment, nevertheless, not much is known about the EPS constituents' specific roles nor how they interact to alter biofilm's functions. We hypothesized that EPS production would be enhanced with the presence of a surface and with a more labile carbon source. Also, that even though carbohydrates and proteins are the main constituents of EPS, we could still find quantifiable amounts of mannosamine and galactosamine (two amino sugars previously shown to be part of microbial biofilms). Ten soil bacterial and ten soil fungal species were cultured with glycerol or starch and with or without a quartz matrix. After a 4-day cultivation, EPS were extracted, and seven constituents were determined: carbohydrates, DNA, proteins, muramic acid, mannosamine, galactosamine, and glucosamine. We found EPS composition was strongly modified by microbial type, whereas differences in EPS production were driven mostly by environmental conditions. The EPS-carbohydrate/protein ratio was higher for cultures grown in starch media than in glycerol and increased in the presence of quartz. EPS-carbohydrate concentration reflected environmental changes of substrate quality and surface presence. Contrastingly, changes in the other EPS constituent composition are likely due to intrinsic microbial characteristics. Our findings open the pathway to study microbial biofilms in more complex environments (such as soils) and shed light to the importance of extracellular structures to microbial processes.

Bacterial dispersal from a biofilm is presently the least-studied step of the biofilm life cycle. The symbiotic bacterial species Vibrio fischeri is a model organism for studying biofilms relevant to a eukaryotic host; however, methodology is lacking to readily study the dispersal of this microbe from biofilms formed in the lab. Here, we adapted a time-lapse assay to visualize biofilm dispersal by V. fischeri. We observed biofilm formation and dispersal for multiple V. fischeri isolates, which displayed a variety of biofilm architecture phenotypes and dispersal dynamics. We then investigated V. fischeri strain ES114 using genetic tools and mutants available for this strain. ES114 exhibited calcium-dependent biofilm formation followed by a rapid (less than 10 min) coordinated dispersal event that occurred approximately 5 h from the experimental start. Biofilm dispersal was largely independent of the dispersal-promoting protease encoded by lapG. Although we found no role under our conditions for either biofilm formation or dispersal for several other factors including polysaccharides and autoinducers, we determined that biofilm formation was enhanced, and dispersal was delayed, with increased concentrations of calcium. Furthermore, biofilm formation depended on the calcium-responsive diguanylate cyclase (DGC) CasA, and dispersal could be modulated by overexpressing CasA. Our work has thus developed a new tool for the V. fischeri field and uncovered a key role for calcium signaling and c-di-GMP in early biofilm formation and dispersal in V. fischeri.

Biofilm formation and dispersal are critical steps in both symbiotic and pathogenic colonization. Relative to biofilm formation, the process of dispersal in the model symbiont Vibrio fischeri, and other bacteria, is understudied. Here, we adapted an imaging assay to study early biofilm formation and the dispersal process in V. fischeri. We demonstrated that our assay can quantify biofilm formation and dispersal over time, can reveal phenotypic differences in diverse natural wild-type isolates, and is sensitive enough to investigate the impact of environmental factors. Our data confirm that calcium is a potent biofilm formation signal and identify the diguanylate cyclase CasA as a key regulator. This work leads the way for more in-depth research about unknown mechanisms of biofilm dispersal.

Active colloidal particles typically exhibit a pronounced affinity for accumulating and being captured at boundaries. Here, we engineer long-range repulsive interactions between colloids that self-propel under an electric field and patterned obstacles. As a result of these interactions, particles turn away from obstacles and avoid accumulation. We show that by tuning the applied field frequency, we precisely and rapidly control the effective size of the obstacles and therefore modulate the particle approach distance. This feature allows us to achieve gating and tunable confinement of our active particles whereby they can access regions between obstacles depending on the applied field. Our work provides a versatile means to directly control confinement and organization, paving the way towards applications such as sorting particles based on motility or localizing active particles on demand.

A significant burden on the healthcare system, microbial contamination of biomedical surfaces can result in hospital-acquired illnesses. Bacteria, viruses, and fungi may live on surfaces for days or months and spread to patients and medical personnel. This article describes the 3D printing technologies, such as fused deposition modeling, bioprinting, binder jetting/inkjet, poly-jet, electron beam manufacturing, stereolithography, selective laser sintering, and laminated object manufacturing used for manufacturing the healthcare setting's surface to reduce bacterial contamination with exploring anti-biofilm activity against different bacterial species responsible for infections, based on the critical evaluation of published reports. This strategy has immense potential to become an upcoming approach for advancing the coating concept on the material's surface in healthcare settings. Our literature evaluation identifies beneficial 3D printing materials and associated technologies against microorganisms' growth, mainly bacteria involved in implant-based infection, emphasizing the development of anti-biofilm 3D-printed surfaces. Additionally, the authors have identified a few key areas where research and development are critically required to advance 3D-printing technology in healthcare settings.

The problem of antimicrobial resistance (AMR) has caused global concern due to its great threat to human health. Evidences are emerging for a critical role of biofilms, one of the natural protective mechanisms developed by bacteria during growth, in resisting commonly used clinical antibiotics. Advances in nanomedicines with tunable physicochemical properties and unique anti-biofilm mechanisms provide opportunities for solving AMR risks more effectively. In this review, we summarize the five "A" stages (adhesion, amplification, alienation, aging and allocation) of biofilm formation and mechanisms through which they protect the internal bacteria. Aimed at the characteristics of biofilms, we emphasize the design "THAT" principles (targeting, hacking, adhering and transport) of nanomedicines in their interactions with biofilms and internal bacteria. Furthermore, recent progresses in multimodal antibacterial nanomedicines, including biofilms disruption and bactericidal activity, and the types of currently available antibiofilm nanomedicines contained organic and inorganic nanomedicines are outlined and highlighted their potential applications in the development of preclinical research. Last but not least, we offer a perspective for the effectiveness of nanomedicines designed to address AMR and challenges associated with their clinical translation.

Increased drying of rivers under global climate change is leading to biodiversity loss. However, it is not clear whether biodiversity loss affects river functions. In this study, we investigated the changes in biofilm community diversity and functions in an artificial stream after different drying durations. A critical drying duration of around 60 days was found in the microbial composition and functions. Therefore, different drying durations can be divided into short-term drying (~0-20 days) and long-term drying (~60-130 days) to analyse the effect of biodiversity in terms of ecosystem functions. In summary, the dominant relationship of biodiversity on community stability got uncoupled after long-term drying. Community assembly became dominant in maintaining multifunctionality with increasing drying duration rather than biodiversity as traditionally perceived. This study reveals the importance of community assembly, extending theoretical knowledge of the relationship between biodiversity and ecosystem multifunctionality.

Statins have been reported for diverse pleiotropic activities, including antimicrobial and antibiofilm. However, due to the limited understanding of their mode of action, none of the statins have gained approval for antimicrobial or antibiofilm applications. In a recent drug repurposing study, we observed that two statins (i.e., Simvastatin and Lovastatin) interact stably with TasA(28-261), the principal extracellular matrix protein of Bacillus subtilis, and also induce inhibition of biofilm formation. Nevertheless, the underlying mechanism remained elusive. In the present study, we examined the impact of these statins on the physiological activity of TasA(28-261), specifically its interaction with TapA(33-253) and aggregation into the amyloid-like structure using purified recombinant TasA(28-261) and TapA(33-253) in amyloid detection-specific in vitro assays (i.e., CR binding and ThT staining assays). Results revealed that both statins interfered with amyloid formation by the TasA(28-261)-TapA(33-253) complex, while neither statin inhibited amyloid formation by lysozyme, a model amyloid-forming protein. Moreover, neither statin significantly altered the expressions of terminal regulatory genes (viz, sinR, sinI) and terminal effector genes (viz, tasA, tapA, and bslA) involved in biofilm formation by B. subtilis. While the intricate interplay between Simvastatin and Lovastatin with the diverse molecular constituents of B. subtilis biofilm remains to be elucidated conclusively, the findings obtained during the present study suggest that the underlying mechanism for Simvastatin- and Lovastatin-mediated inhibition of B. subtilis biofilm formation is manifested by interfering with the aggregation and amyloid formation by TasA(28-261)-TapA(33-253). These results represent one of the first experimental evidence for the underlying mechanism of antibiofilm activity of statins and offer valuable directions for future research to harness statins as antibiofilm therapeutics.

This work aims to encapsulate Bacillus licheniformis PPL2016 (12 × 106 CFU/mL), a marine probiotic characterized at a biochemical and molecular level, in sodium alginate (2%) microparticles and to evaluate its controlled and directed release in a simulated digestive system (DS) of the swimming crab Callinectes arcuatus, considering the following age classes and sexes: Adult Female, Juvenile Female, Adult Male, and Juvenile. The encapsulation process was carried out using the ionic gelation technique. The microcapsules were characterized physiochemically by their size, morphology, number of encapsulated bacteria after the encapsulation process, as well as bacterial survival after 45 days of storage (4 °C). The in vitro release and survival studies of bacteria inside the organs that make up the DS of C. arcuatus were carried out using a protocol developed in our laboratory by applying extracts of dissected organs from the DS (stomach, hepatopancreas and intestine) of the swimming crab. A χ2 test (α = 0.05) was performed at linearization (Log10) of the percentages of the controlled releases of microencapsulated B. licheniformis PPL2016 at different times (0 h, 4 h, 8 h, 12 h), corresponding to the extracts of the organs which simulated the digestive system of C. arcuatus. After biochemical characterization B. licheniformis PPL2016 was considered probiotic bacteria. Microparticles with an average size of 602 to 639 µm were obtained after using the ionic gelation method. Bacterial survival and encapsulation efficacy showed high cell viability and performance above 77.94%. Stability studies showed that storage at a temperature of 4 °C, kept almost 100% of viable bacteria for 15 days; however, cell viability decreased to a survival of 90% after 30 days of storage at this temperature. Regardless of reduced cell viability after 30 days, there are enough viable bacterial cells. Release and survival studies showed that alginate particles had a protective effect on bacteria, these results suggest that microparticles can be produced by a low-cost method. In juvenile males, the percentage of release of probiotic bacteria was greater in TIV in the enzyme extract of the intestine (12 h) with 95 ± 0.45%. Juvenile males had the lowest in vitro release at the stomach stage (0 h) and thus marks the significance for their low release of microcapsules at the beginning of the in vitro release (χ2 = 6.7509; χ2Calculated Pool = 13.5188; χ2Calculated Critical (0.05, 21) = 11.5919; p < 0.05), with the highest significance in the intestine (12 h) (χ2 = 1.2602; χ2Calculated Pool = 13.5188; χ2Calculated Critical (0.05, 21) = 11.5919; p < 0.05). Significant differences in vitro bacterial release were recorded for age classes and sexes of C. arcuatus.

The antimicrobial effect of antimicrobial peptides is typically slow; they can be rapidly biodegraded and often have non-selective toxicity and elaborate sequences. Here we report a short peptide that is activated by ultrasound, that shows high broad-spectrum antibacterial efficiency (>99%) against clinically isolated methicillin-resistant bacteria (specifically, Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis, Enterobacter cancerogenus and Pseudomonas aeruginosa) with 15 min of ultrasound irradiation, and that has negligible toxicity and low self-antibacterial activity. We selected the peptide, FFRKSKEK (a segment from the human host-defence LL-37 peptide), from a library of peptides with piezoelectric diphenylalanine (FF) sequences, low toxicity, hydrophobicity and net positive charge. We show via all-atom molecular dynamics simulations that ultrasound amplifies the membrane-penetrating ability of peptides with FF sequences and that its piezoelectric polarization generates reactive-oxygen species and disturbs bacterial electron-transport chains. In a goat model of hard-to-treat intervertebral infection, the sonosensitive peptide led to better outcomes than vancomycin. Antimicrobial peptides activated by ultrasound may offer a clinically relevant strategy for combating antibiotic-resistant infections.

Biofilms are emerging platforms for the production of valuable compounds. The present study is the first to assess the capacity of Escherichia coli biofilms to produce curcumin through the expression of a biosynthetic pathway involving three genes: 4-coumarate-CoA ligase (4CL), diketide-CoA synthase (DCS), and curcumin synthase (CURS). The effects of chemical induction with isopropyl β-d-1-thiogalactopyranoside (IPTG) and ferulic acid (FA), and the incubation temperature on biofilm formation and curcumin production were evaluated. Biofilms were formed in 12-well microtiter plates over three days and then induced with 1 mM IPTG and FA at 2 or 8 mM. After induction, the samples were incubated for two days at 26 or 30 °C. Total and culturable planktonic and biofilm cells, as well as biofilm thickness and volumetric and specific curcumin production, were assessed on days 3, 4, and 5. The results demonstrated that biofilms produced up to 10-fold higher curcumin levels (0.9-2.2 fg·cell-1) than their planktonic counterparts (0.1-0.3 fg·cell-1). The highest specific curcumin production (2.2 fg·cell-1) was achieved using 8 mM FA. However, no significant differences in curcumin production were observed between the induced samples incubated at the tested temperatures. These results validated the potential of biofilm systems for expressing a complete exogenous biosynthetic pathway using metabolic engineering, particularly for curcumin production.

Biofilm formation is a mechanism exhibited by bacteria, making them 10-1000 times more resistant than planktonic cells. The aim was to collect the most suitable characteristics from already available antibiofilm peptides and design novel antibiofilm peptide sequences along with these characteristics altogether in one sequence.

Antibiofilm peptides were collected from AMP database (APD3), and sequence analysis was performed to derive the most suitable features. An artificial design approach, modified database filtering technology, was chosen to design novel peptide sequences, and their activity was predicted by machine-learning prediction models. Antibacterial and antibiofilm potential of the selected peptide sequence (arginine-based peptide 12; RbP12) was assessed against Staphylococcus aureus P10 and Pseudomonas aeruginosa PA64.

A total of 34 peptides were designed, of which 22 were arginine based and 12 were serine based. All the designed peptides were predicted to have antibiofilm properties. RbP12 was found to inhibit the growth of S. aureus P10 completely at an MIC of 85 mg/L, while the percentage inhibition of P. aeruginosa PA64 was calculated to be 32.1%. Significant inhibition of biofilms by RbP12 was observed in the case of both S. aureus P10 and P. aeruginosa PA64. An MTT assay showed no significant cytotoxicity by RbP12 with 96% cell viability.

RbP12 was found to have higher antibacterial and antibiofilm activity against S. aureus P10 compared with P. aeruginosa PA64. With 96% cell viability, usage of RbP12 on human skin is totally safe. Based on these results, the aim is to develop self-assembled peptide hydrogels for wound healing in future work.

Salmonella Enteritidis is a major poultry-associated foodborne pathogen that can form sanitizer-tolerant biofilms on various surfaces. The biofilm-forming capability of S. Enteritidis facilitates its survival on farm and food processing equipment. Conventional sanitization methods are not completely effective in killing S. Enteritidis biofilms. This study investigated the efficacy of a Generally Recognized as Safe phytochemical Trans-cinnamaldehyde (TC), and in its nanoemulsion form (TCNE), for inhibiting S. Enteritidis biofilm formation and inactivating mature biofilms developed on polystyrene and stainless-steel surfaces. Moreover, the effect of TC on Salmonella genes critical for biofilm formation was studied. TCNE was prepared using a high energy sonication method with Tween 80. For biofilm inhibition assay, S. Enteritidis was allowed to form biofilms either in the presence or absence of sub-inhibitory concentration (SIC; 0.01 %) of TCNE at 25°C and the biofilm formed was quantified at 24-h intervals for 48 h. For the inactivation assay, S. Enteritidis biofilms developed at 25°C for 48 h were exposed to TCNE (0.5, 1 %) for 1, 5, and 15 min, and surviving S. Enteritidis in the biofilm were enumerated. SIC of TCNE inhibited S. Enteritidis biofilm by 45 % on polystyrene and 75 % on steel surface after 48 h at 25°C compared to control (P < 0.05). All TCNE treatments rapidly inactivated S. Enteritidis mature biofilm on polystyrene and steel surfaces (P < 0.05). The lower concentration of TCNE (0.5 %) reduced S. Enteritidis counts by 1.5 log CFU/ml as early as 1 min of exposure on both polystyrene and stainless-steel surfaces. After 15 min of exposure, TCNE at concentration of 0.5 or 1 % reduced S. Enteritidis count significantly by 4.5 log CFU or 6 log CFU/ml on polystyrene or stainless-steel surfaces. TC downregulated the expression of S. Enteritidis genes (hilA, hilC, flhD, csgA, csgD, sdiA) responsible for biofilm formation (P < 0.05). Results suggest that TCNE has potential as a natural disinfectant for controlling S. Enteritidis biofilms on common farm and food processing surfaces, such as plastic and steel.

The presence of microbial biofilms on equipment surfaces is a recurrent problem in the food industry. To reduce the risk of biofilm development, a preventive method based on photoactive antibacterial surfaces is proposed. In the present study, crystalline rutile form titanium dioxide (TiO2) thin layers are deposited on stainless steel substrates by RF sputtering under reactive plasma. Such layers are assessed for their bactericidal activity on two strains of Listeria monocytogenes. After 1 h of irradiation under UV-A at 365 nm, a decrease of 2 log of the number of adherent Listeria cells is observed. Analysis with scanning electron microscopy suggests damages to the bacterial walls. Moreover, the peroxidation of the membrane lipids of L. monocytogenes by the radical species formed by photocatalysis is confirmed since malondialdehyde was detected after irradiation. Furthermore, the present work investigates the role of the redox species generated by photocatalysis. Indeed, experiments carried out in the presence of scavenger molecules (DMSO, EDTA-2Na, superoxide dismutase) show that holes are the main redox species involved in the antibacterial activity of the deposited layers. These results allow a better understanding of the role of the redox species generated by the photocatalytic activity of the rutile TiO2 thin layers.

Photosensitizers (PSs) capable of in situ oxygen (O2) production are attractive for overcoming hypoxia in photodynamic therapy (PDT). However, these PSs generally require multiple components and complex fabrication procedures, preventing their clinical translation. Herein, we develop a single-component nanophotosensitizer via simple self-assembly that enables cascade production of in situ O2 and singlet oxygen (1O2) for superior antibacterial PDT (aPDT). Perylene tetracarboxylic acid (PTA) molecules self-assemble into nanophotosensitizers (PTA NPs). Mechanism studies reveal dual functionality of PTA NPs due to their antiparallel-displaced π-π stacking. Aggregated PTA molecules undergo intermolecular electron transfer to yield substantial photogenerated holes, while unimolecular PTA undergoes intersystem crossing to produce triplet PS (3PS*). These holes effectively oxidize water into O2 in situ, which then participates in downstream photosensitization with 3PS* to yield 1O2. This cascade reaction affords PTA NPs with continuous O2 supply and efficient 1O2 production, enabling a 63.07% higher antibacterial rate compared with the clinical antibiotic vancomycin.

Biofilms are highly organized, cooperating communities of microorganisms encased in a self-produced extracellular matrix, providing resilience against external stress such as antimicrobial agents and host defenses. A hallmark of biofilms is their phenotypic heterogeneity, which enhances the overall growth and survival of the community. In this study, we demonstrate that removing the dnaK and tig genes encoding the core molecular chaperones DnaK (Hsp70 homolog) and Trigger factor disrupted protein homeostasis in Bacillus subtilis and resulted in the formation of an extremely mucoid biofilm with aberrant architecture, compromised structural integrity, and altered phenotypic heterogeneity. These changes include a large reduction in the motile subpopulation and an overrepresentation of matrix producers and endospores. Overproduction of poly-γ-glutamic acid contributed crucially to the mucoid phenotype and aberrant biofilm architecture. Homeostasis impairment, triggered by elevated temperatures, in wild-type cells led to mucoid and aberrant biofilm phenotypes similar to those observed in strains lacking both dnaK and tig. Our findings show that disruption of protein homeostasis, whether due to the absence of molecular chaperones or because of environmental factors, severely changes biofilm features.

Bacteria synthesize chemically diverse capsular and secreted polysaccharides that function in many physiological processes and are widely used in industrial applications. In the ubiquitous Wzx/Wzy-dependent biosynthetic pathways for these polysaccharides, the polysaccharide co-polymerase (PCP) facilitates the polymerization of repeat units in the periplasm, and in Gram-negative bacteria, also polysaccharide translocation across the outer membrane. These PCPs belong to the PCP-2 family, are integral inner membrane proteins with extended periplasmic domains, and functionally depend on alternating between different oligomeric states. The oligomeric state is determined by a cognate cytoplasmic bacterial tyrosine kinase (BYK), which is either part of the PCP or a stand-alone protein. Interestingly, BYK-like proteins, which lack key catalytic residues and/or the phosphorylated Tyr residues, have been described. In Myxococcus xanthus, the exopolysaccharide (EPS) is synthesized and exported via the Wzx/Wzy-dependent EPS pathway in which EpsV serves as the PCP. Here, we confirm that EpsV lacks the BYK domain. Using phylogenomics, experiments, and computational structural biology, we identify EcpK as important for EPS biosynthesis and show that it structurally resembles canonical BYKs but lacks residues important for catalysis and Tyr phosphorylation. Using proteomic analyses, two-hybrid assays, and structural modeling, we demonstrate that EcpK directly interacts with EpsV. Based on these findings, we suggest that EcpK is a BY pseudokinase and functions as a scaffold, which by direct protein-protein interactions, rather than by Tyr phosphorylation, facilitates EpsV function. EcpK and EpsV homologs are present in other bacteria, suggesting broad conservation of this mechanism and establishing a phosphorylation-independent PCP-2 subfamily.IMPORTANCEBacteria produce a variety of polysaccharides with important biological functions. In Wzx/Wzy-dependent pathways for the biosynthesis of secreted and capsular polysaccharides in Gram-negative bacteria, the polysaccharide co-polymerase (PCP) is a key protein that facilitates repeat unit polymerization and polysaccharide translocation across the outer membrane. PCP function depends on assembly/disassembly cycles that are determined by the phosphorylation/dephosphorylation cycles of an associated bacterial tyrosine kinase (BYK). Here, we identify the BY pseudokinase EcpK as essential for exopolysaccharide biosynthesis in Myxococcus xanthus. Based on experiments and computational structural biology, we suggest that EcpK is a scaffold protein, guiding the assembly/disassembly cycles of the partner PCP via binding/unbinding cycles independently of Tyr phosphorylation/dephosphorylation cycles. We suggest that this novel mechanism is broadly conserved.

The increasing prevalence of antibiotic resistance, driven by the overuse and misuse of conventional antibiotics, has become a critical public health concern. Photothermal antibacterial therapy (PTAT) utilizes heat generated by photothermal agents under light exposure to inhibit bacterial growth without inducing resistance, attracting more and more attention. Quinoid conjugated polymers, especially para-azaquinodimethane (AQM) polymer, are a class of organic semiconductors known for efficient π-electron delocalization, near-infrared absorption, and narrow bandgap, showing great potential in the application of photothermal reagents. However, current AQM polymers face challenges related to their solubility, photostability, and biocompability. In this study, tetraglycol is introduced onto the AQM core for improving the drawbacks of the resulting polymers. Two AQM polymers with different electron donor (thiophene and 2,2'-bithiophene) are synthesized and evaluated for their various properties. PAQMT exhibited superior performance, including higher extinction coefficients, improved light absorption, and greater stability under repeated NIR irradiation. PAQMT is further developed into nanoparticles via encapsulation, resulting in excellent colloidal stability, effective bacterial inhibition under 808 nm NIR light. This work provides new strategy in improving the solubility, photostability, and photothermal properties of AQM polymers, offers opportunities for promoting the application of quinoidal conjugated polymers in PTAT.

Antibiofilm treatment, particularly drug-containing wound healing dressings, does not typically penetrate the robust protective extracellular polymeric substance of biofilm and eradicate the bacteria. Here, a rational design of nitric oxide (NO) donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine (BNN6)-based injectable hydrogel, is reported in which the NO release can be triggered by a photothermal effect owing to semiconducting perylene diimide (PDI) J-aggregation fibers. The synthetic PDI derivatives self-assembling into 0D nanoparticles and then aggregating to 1D J fiber is accompanied by absorbance red-shifting from 700 to 790 nm and then to 852 nm. After encapsulating BNN6, a "sandwich roll" (SR) like structure is evenly crosslinked into an injectable hydrogel (SRH) exhibiting a high photothermal convenience efficiency of 72%, which enables the SRH to achieve highly efficient photocontrol NO release. The SRH shows excellent injectability, shape adaptability, and effective antibacterial efficacy over 99% to the E.coli and S. aureus. and remarkable in vivo antibiofilm efficiency of 99.58% by laser irradiation. Furthermore, the synergistic treatment displays the ability to eliminate inflammation, facilitate angiogenesis, and promote collagen deposition, thereby significantly stimulating the healing process of wounds. The semiconducting J-aggregation injectable hydrogel can be a versatile strategy for the treatment of biofilm.

The inflammatory response triggered by the interaction between implants and macrophages is essential for bone regeneration around these implants. This study presents the application of dopamine hydrochloride to develop a copper and procyanidins coating on titanium surfaces to investigate its effects on bacterial inhibition, macrophage polarization, and osteogenic differentiation. The results demonstrated that this copper/procyanidins coating significantly suppressed the growth of Escherichia coli and Staphylococcus aureus. Notably, the initial release of Cu2+ ions promoted macrophage polarization toward a pro-inflammatory phenotype while stimulating the secretion of anti-inflammatory factors. Subsequently, the reduced Cu2+ release combined with procyanidins facilitated the transition from M1 to M2 macrophages-an essential process for bacterial phagocytosis and bone regeneration. Furthermore, this coating enhanced the secretion of osteogenic factors by bone marrow mesenchymal stem cells, enhancing their osteogenic differentiation and integration with bone tissue. These findings highlight the potential of copper/procyanidins coating in developing implant surfaces with immune-modulating and sustained antibacterial properties.

The opportunistic bacterial pathogen Pseudomonas aeruginosa is a leading cause of antimicrobial resistance-related deaths, and novel antimicrobial therapies are urgently required. P. aeruginosa infections are difficult to treat due to the bacterium's propensity to form biofilms, whereby cells aggregate to form a cooperative, protective structure. Autolysis, the self-killing of bacterial cells, and the bacterial cell-to-cell communication system, quorum sensing (QS), play essential roles in biofilm formation. Strains of P. aeruginosa that have lost the lasI/R QS system commonly develop in patients, and previous studies have characterized distinctive autolysis phenotypes in these strains. Yet, the underlying causes and implications of these autolysis phenotypes remain unknown. This study confirmed these autolysis phenotypes in the PA14 QS mutant strains, ΔlasI and ΔlasR, and investigated the consequences of QS loss and associated autolysis on biofilm formation and antibiotic susceptibility. QS mutants exhibited delayed biofilm formation but ultimately surpassed the wild-type (WT) in biofilm mass. However, the larger biofilm mass of the QS mutants was not reflected in higher live-cell numbers, indicating an altered biofilm structure. Nevertheless, QS mutant biofilms were not more susceptible to antibiotics than the WT. Artificial supplementation of ΔlasI with a QS signal molecule (autoinducer) restored the strain's QS system without the associated costs of QS, enabling ΔlasI to achieve higher pre-treatment and post-treatment live-cell numbers. Overall, the lack of QS functioning was not detrimental to biofilm antibiotic tolerance, though the artificial disruption of QS may reduce the advantages of QS mutants within in vivo mixed-strain populations. Much remains to be understood regarding the regulation and induction of the autolysis phenotypes observed in these strains, and future research to fully elucidate the control and consequences of autolysis may offer potential for novel antimicrobial therapies.

Foods prepared through heating, including broths, have the potential and risk of survival of Bacillus cereus, which has the ability to form spores and biofilms. This study evaluated the efficacy of various natural products (particularly spices) in mitigating B. cereus contamination in Cheonggukjang jjigae (CJ) broth. The following characteristics of B. cereus were examined: viability of vegetative cells (including other pathogenic bacteria) and planktonic spores, heat resistance of planktonic spores and spores in intact biofilms, and biofilm formation and persistence. In an antimicrobial test to evaluate the inhibitory effects of spice and cruciferous vegetable extracts on B. cereus CH3 vegetative cells, cinnamon, garlic, and rosemary extracts were selected as they have shown significant inhibitory effects, with inhibition zones of 20-29 mm in diameter at the highest concentration tested (160 mg/mL, unless otherwise stated). These spice extracts also exhibited antimicrobial activity against other foodborne pathogens, including Staphylococcus aureus, Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli O157:H7. Garlic extract showed the greatest inhibitory effect on the viability and heat resistance of planktonic spores of B. cereus CH3, and cinnamon and rosemary extracts exhibited similar effects. Garlic extract reduced B. cereus CH3 spore counts in phosphate buffer solution (PBS) and CJ broth by 20.22 % and 14.08 %, respectively, compared to control (treated with the same ethanol amount instead of the extract), and effectively weakened spore heat resistance, reducing the D100°C-values of planktonic spores of B. cereus CH3 in PBS and CJ broth by 32.89 % and 23.08 %, respectively, compared to control. As for the characteristics related to biofilm, garlic extract showed the highest inhibitory effect on biofilm formation and persistence and heat resistance of spores in intact biofilms, followed by rosemary and cinnamon extracts. All three spice extracts completely inhibited biofilm formation even at the lowest concentration (20 mg/mL) at the early stage of biofilm formation. They completely eradicated biofilm persistence formed in brain heart infusion (BHI) and CJ broth at the highest concentration. A high garlic extract concentration (80 mg/mL) also reduced the D100°C-values of spores in biofilms formed in BHI and CJ broth by 16.34 % and 9.00 %, respectively, compared to control. Taken together, garlic extract was most effective in mitigating B. cereus contamination in a concentration-dependent manner in in vitro-menstrua and CJ broth. This study may provide one of the promising strategies to reduce the risk of B. cereus in soybean stews such as CJ.

This qualitative review aims to summarize current knowledge on ventriculostomy-related infection (VRI) pathophysiology and its prevention. VRI generally occurs at day 10, mainly because of Gram-positive cocci , after a cerebrospinal fluid leak. Skin microbiota and biofilm seem to play a major role in VRI pathogenesis. Colonization of external ventricular drain by biofilm is universal and occurs quickly after catheter insertion. However, pathogens from the skin are more often associated with VRI than commensal bacteria. A review of proposed preventive measures shows that none has proven to be fully efficient. Periprocedural and prolonged systemic prophylactic antimicrobials have not shown to prevent VRIs and may promote the emergence of more resistant or pathogenic strains. Antimicrobial and silver-impregnated external ventricular drains, although promising, have not demonstrated preventive effects and may modify bacterial ecology. These results are consistent with the proposed pathophysiology. Finally, we will present a few propositions for future research that may help in improving our knowledge and thus better prevent VRIs. Until then, given the available data, limiting the duration of ventricular drainage may be the most attainable option to prevent VRIs.

Numerous types of contemporary antibiotic treatment regimens have become ineffective with the increasing incidence of drug tolerance. As a result, it is pertinent to seek novel and innovative solutions such as antibacterial nanomaterials (NMs) for the prohibition and treatment of hazardous microbial infections. Unlike traditional antibiotics (e.g., penicillin and tetracycline), the unique physicochemical characteristics (e.g., size dependency) of NMs endow them with bacteriostatic and bactericidal potential. However, it is yet difficult to mechanistically predict or decipher the networks of molecular interaction (e.g., between NMs and the biological systems) and the subsequent immune responses. In light of such research gap, this review outlines various mechanisms accountable for the inception of drug tolerance in bacteria. It also delineates the primary factors governing the NMs-induced molecular mechanisms against microbes, specifically drug-resistant bacteria along with the various NM-based mechanisms of antibacterial activity. The review also explores future directions and prospects for NMs in combating drug-resistant bacteria, while addressing challenges to their commercial viability within the healthcare industry.

The rising prevalence of fungal infections, especially those caused by Candida species, presents a major risk to global health. With approximately 1.5 million deaths annually, the urgency for effective treatment options has never been greater. Candida spp. are the leading cause of invasive infections, significantly impacting immunocompromised patients and those in healthcare settings. C. albicans, C. parapsilosis and the emerging species C. auris are categorized as highly dangerous species because of their pathogenic potential and increasing drug resistance. This review comparatively describes the formation of microbial biofilms of both bacterial and fungal origin, including major pathogens, thereby creating a novel focus. Biofilms can further complicate treatment, as these structures provide enhanced resistance to antifungal therapies. Traditional antifungal agents, including polyenes, azoles and echinocandins, have shown effectiveness, yet resistance development continues to rise, necessitating the exploration of novel therapeutic approaches. Antimicrobial peptides (AMPs) such as the anti-biofilm peptides Pom-1 and Cm-p5 originally isolated from snails represent promising candidates due to their unique mechanisms of action and neglectable cytotoxicity. This review article discusses the challenges posed by Candida infections, the characteristics of important species, the role of biofilms in virulence and the potential of new therapeutic options like AMPs.

Infectious diseases pose considerable challenges to public health, particularly with the rise of multidrug-resistant pathogens that globally cause high mortality rates. These pathogens can persist on surfaces and spread in public and healthcare settings. Advances have been made in developing antimicrobial materials to reduce the transmission of pathogens, including materials composed of naturally sourced polyphenols and their derivatives, which exhibit antimicrobial potency, broad-spectrum activity, and a lower likelihood of promoting resistance. This review provides an overview of recent advances in the fabrication of antimicrobial phenolic biomaterials, where natural phenolic compounds act as active antimicrobial agents or encapsulate other antimicrobial agents (e.g., metal ions, antimicrobial peptides, natural biopolymers). Various forms of phenolic biomaterials synthesized through these two strategies, including antimicrobial particles, capsules, hydrogels, and coatings, are summarized, with a focus on their application in wound healing, bone repair and regeneration, oral health, and antimicrobial coatings for medical devices. The potential of these advanced phenolic biomaterials provides a promising therapeutic approach for combating antimicrobial-resistant infections and reducing microbial transmission.

In aquatic environments, antibiotics degrade into byproducts, potentially enhancing bacterial resistance. However, the specific mechanisms by which these byproducts induce bacterial resistance remain elusive. This study conducted experimental evolution experiments to explore how E. coli adapts to tetracycline (TC) and its primary degradation products-anhydrotetracycline (ATC), epitetracycline (ETC), and 4-epianhydrotetracycline (EATC)-through evolution experiments. Prolonged exposure to TC and its byproducts significantly increased frequency of resistant mutants in E. coli ATCC25922, with a maximum 106-fold increase. Resistant mutants exhibited markedly elevated minimum inhibitory concentrations (MICs) for TC, ampicillin (AMP), and ciprofloxacin (CIP), indicating multidrug resistance. Transcriptomic analysis showed that the antibiotic resistance phenotype could be related to enhanced target protection, metabolic adaptations, and reduced membrane permeability. The induction pathways between TC and its byproducts were distinct. Specifically, TC20d (where TC20d represents the mutants collected after 20 days of continuous exposure to TC) was associated with more alterations in ribosome-associated genes, which was correlated with an enhanced defensive response as shown by the data. Moreover, variations in energy metabolism gene expression suggest a robust metabolic defense in ATC20d and ETC20d. When TC and its byproducts-ATC, ETC, and EATC-act together, they induce antibiotic resistant mutants at rates of 29.8 %, 18.9 %, 18.3 %, and 31.9 %, respectively. This study provides a descriptive overview of the possible adaptive mechanisms and pathways that may be involved in antibiotic resistance due to environmental exposure.

Biofilms are structurally organized communities of microorganisms that adhere to a variety of surfaces. These communities produce protective matrices consisting of polymeric polysaccharides, proteins, nucleic acids, and/or lipids that promote shared resistance to various environmental threats, including chemical, antibiotic, and immune insults. While algal and bacterial biofilms are more apparent in the scientific zeitgeist, many fungal pathogens also form biofilms. These surprisingly common biofilms are morphologically distinct from the multicellular molds and mushrooms normally associated with fungi and are instead an assemblage of single-celled organisms. As a collection of yeast and filamentous cells cloaked in an extracellular matrix, fungal biofilms are an extreme threat to public health, especially in conjunction with surgical implants. The encapsulated yeast, Cryptococcus neoformans, is an opportunistic pathogen that causes both pulmonary and disseminated infections, particularly in immunocompromised individuals. However, there is an emerging trend of cryptococcosis among otherwise healthy individuals. C. neoformans forms biofilms in diverse environments, including within human hosts. Notably, biofilm association correlates with increased expression of multiple virulence factors and increased resistance to both host defenses and antifungal treatments. Thus, it is crucial to develop novel strategies to combat fungal biofilms. In this review, we discuss the development and treatment of fungal biofilms, with a particular focus on C. neoformans.

Reviewing the literature published up to October 2024.Sesterterpenoids are one of the most chemically diverse and biologically promising subgroup of terpenoids, the largest family of secondary metabolites. The present review article summarizes more than seven decades of studies on isolation and characterization of more than 1600 structurally novel sesterterpenoids, supplemented by biological, pharmacological, ecological, and geographic distribution data. All the information have been implemented in eight tables available on the web and a relational database https://sesterterpenoids.unige.net/. The interface has two sections, one open to the public for reading only and the other, protected by an authentication mechanism, for timely updating of published results.

The search for life elsewhere in the universe has remained one of the main goals of astrobiological exploration. In this quest, extreme environments on Earth have served as analogs to study the potential habitability of Mars and icy moons, which include but are not limited to hydrothermal vent systems, acid lakes, deserts, and polar ice, among others. Within the various forms that life manifests, biofilms constitute one of the most widespread phenotypes and are ubiquitous in extreme environments. Biofilms are structured communities of microorganisms enclosed in a matrix of extracellular polymeric substances (EPS) that protect against unfavorable and dynamic conditions. These concentrated structures and their associated chemistry may serve as unique and persistent signatures of life processes that may aid in their detection. Here we propose biofilms as a model system to understand the habitability of extraterrestrial systems and as sources of recognizable and persistent biosignatures for life detection. By testing these ideas in extreme analog environments on Earth, this approach could be used to guide and focus future exploration of samples encompassing the geologic record of early Earth as well as other planets and moons of our solar system.

Nonhealing chronic bacterial infections are very challenging to both patients and the healthcare-providing system. Multimodal therapy enhances the antibiotic efficacy to treat infections via combating multidrug resistance through cumulative therapeutic effects. Functionalized polydopamine (PDA)-coated Bi particles having a core-shell structure may treat such chronic infections. We fabricated a new advanced material based on Tris-functionalized PDA and Bi using a facile three-step protocol for healing drug-resistant bacterial infections. The fabrication of Bi particles, PDA coating on Bi particles, and their Tris functionalization were confirmed by X-ray diffraction, and spectroscopic and thermogravimetric analyses. Tris-functionalized PDA-coated Bi particles, abbreviated as Bi/PDA-Tris, exhibited a higher average diameter, improved hydrophilicity, aqueous dispersity, and colloidal stability. Bi/PDA-Tris showed a delicate surface morphology, narrow size distribution, spherical shape, and core-shell structure. In vitro bovine serum albumin and hemolysis assays showed minimal protein adsorption and the desirable hemocompatibility of Bi/PDA-Tris. Antibacterial gentamicin (GM)-immobilized Bi/PDA-Tris showed pH-mediated sustained drug release kinetics under acidic conditions. The in vitro study of GM-loaded Bi/PDA-Tris particles exhibited significant bacterial growth inhibition and bactericidal activity. Tris functionalization effectively enhances the antibacterial efficacy of the PDA shell under acidic conditions to target and heal bacterial infections. This approach has introduced economic, nontoxic, easy-to-use, relatively more biocompatible Bi particles as a substituent for precise metals like Pt, Au, and Ag for the development of core-shell composite materials.

Biofilm formed by Pseudomonas aeruginosa is a three dimensional microbial matrix that confers multidrug resistance properties along with the proficiency to evade the host immune system. The present study aims to determine the combinatorial effects of vitamin D3 (cholecalciferol) with two already reported antibiofilm agents: streptomycin and thymoquinone separately against P. aeruginosa biofilms. The minimum inhibitory concentration of streptomycin, thymoquinone and D3 was found to be 20, 10 and 100 μg/mL respectively. The inhibition of biofilm formation and pre-formed biofilm disintegration properties of streptomycin and thymoquinone alone or in combination with D3 at their sub-MIC concentration was determined by crystal violet staining and confocal laser scanning microscopy. A significant inhibition of metabolic activities like oxygen consumption rate and reduction in quorum sensing related cellular activities like swarming motilities, pyocyanin production and extracellular protease secretion by P. aeruginosa were also observed as a result of this combinatorial effect. Both of these combinatorial applications were found to accumulate ROS in bacterial cells, which has been proved to be one of the main causes of their antibiofilm activity. Effect of these two drug combinations on bacterial lettuce leaf infection was also evaluated. Molecular docking analysis indicated that thymoquinone combined D3 can interact more efficiently with the quorum sensing proteins LasI and LasR. The host cell cytotoxicity of these two combinations was found to be negligible on the murine macrophage cell line. These findings suggest that D3 potentiates the antimicrobial and antibiofilm efficacy of both streptomycin and thymoquinone against P. aeruginosa. Although both combinations have shown significant antibiofilm and antimicrobial potential, combinatorial performances of D3 combined thymoquinone were found to be more promising.

For over 100 years, Bacillus thuringiensis (Bt) has been used as an agricultural biopesticide to control pests caused by insect species in the orders of Lepidoptera, Diptera and Coleoptera. Under nutrient starvation, Bt cells differentiate into spores and associated toxin crystals that can adopt biofilm-like aggregates. We reveal that such Bt spore/toxin biofilms are embedded in a fibrous extrasporal matrix (ESM), and using cryoID, we resolved the structure and molecular identity of an uncharacterized type of pili, referred to here as Fibrillar ENdospore Appendages or 'F-ENA'. F-ENA are monomolecular protein polymers tethered to the exosporium of Bt and are decorated with a flexible tip fibrillum. Phylogenetic analysis reveals that F-ENA is widespread not only in the class Bacilli, but also in the class Clostridia, and the cryoEM structures of F-ENA filaments from Bacillus, Anaerovorax and Paenibaccilus reveal subunits with a generic head-neck domain structure, where the b-barrel neck of variable length latch onto a preceding head domain through short N-terminal hook peptides. In Bacillus, two collagen-like proteins (CLP) respectively tether F-ENA to the exosporium (F-Anchor), or constitute the tip fibrillum at the distal terminus of F-ENA (F-BclA). Sedimentation assays point towards F-ENA involvement in spore-spore clustering, likely mediated via F-BclA contacts and F-ENA bundling through the antiparallel interlocking of the head-neck units.

Antibiotic resistance is currently one of the most significant threats to global public health and safety. And studies have found that over the next 25 years, 39 million people will die directly and 169 million indirectly due to antibiotic-resistant diseases. Consequently, the development of new types of antimicrobial drugs is urgently needed. Antimicrobial peptides (AMPs) constitute an essential component of the innate immune response in all organisms. They exhibit a distinctive mechanism of action that endows them with a broad spectrum of biological activities, including antimicrobial, antibiofilm, antiviral, and anti-inflammatory effects. However, AMPs also present certain limitations, such as cytotoxicity, susceptibility to protein hydrolysis, and poor pharmacokinetic properties, which have impeded their clinical application. The development of delivery systems can address these challenges by modifying AMP delivery and enabling precise, controlled release at the site of infection or disease. This review offers a comprehensive analysis of the mechanisms of action and biological advantages of AMPs. and systematically evaluate how emerging drug delivery systems, such as nanoparticles and hydrogels, enhance the stability and bioavailability of AMPs, discussing both their strengths and limitations. Moreover, unlike previous reviews, this review highlight the most recent clinically approved AMP-based drugs and those currently in development, emphasizing the key challenges in translating these drugs into clinical practice. With these perspectives, it is hoped that this review will provide some insights into overcoming translational barriers and advancing AMPs drugs into clinical practice.