Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 14, 2017; 23(42): 7584-7593
Published online Nov 14, 2017. doi: 10.3748/wjg.v23.i42.7584
Diversity of bacterial lactase genes in intestinal contents of mice with antibiotics-induced diarrhea
Cheng-Xing Long, Lu He, Yan-Fang Guo, Ya-Wei Liu, Nen-Qun Xiao, Zhou-Jin Tan
Cheng-Xing Long, Lu-He, Yan-Fang Guo, Ya-Wei Liu, Nen-Qun Xiao, Zhou-Jin Tan, Department of Microbiology, Hunan University of Chinese Medicine, Changsha 410208, Hunan Province, China
Cheng-Xing Long, College of Mathematics and Finance, Hunan University of Humanities, Science and Technology, Loudi 417000, Hunan Province, China
Author contributions: Tan ZJ designed the study; He L and Guo YF performed the experiments; Liu YW and Long CX analyzed the data; Long CX and Xiao NQ wrote the paper.
Supported by the National Natural Science Foundation of China, No. 81573951.
Institutional review board statement: The study was approved by the Institutional Review Board of Hunan University of Chinese Medicine, Changsha, China.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Animal Ethics and Welfare Committee of Hunan University of Chinese Medicine, Animal License SCXK (Xiang) 2013-0004.
Conflict-of-interest statement: The authors declare no conflict of interest related to this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Zhou-Jin Tan, PhD, Professor, Department of Microbiology, Hunan University of Chinese Medicine, 300 Xueshi Road, Changsha 410208, Hunan Province, China. tanzhjin@sohu.com
Telephone: +86-13974954942
Received: July 16, 2017
Peer-review started: July 18, 2017
First decision: August 30, 2017
Revised: September 14, 2017
Accepted: September 26, 2017
Article in press: September 26, 2017
Published online: November 14, 2017
Abstract
AIM

To investigate the diversity of bacterial lactase genes in the intestinal contents of mice with antibiotics-induced diarrhea.

METHODS

Following 2 d of adaptive feeding, 12 specific pathogen-free Kunming mice were randomly divided into the control group and model group. The mouse model of antibiotics-induced diarrhea was established by gastric perfusion with mixed antibiotics (23.33 mL·kg-1·d-1) composed of gentamicin sulfate and cephradine capsules administered for 5 days, and the control group was treated with an equal amount of sterile water. Contents of the jejunum and ileum were then collected and metagenomic DNA was extracted, after which analysis of bacterial lactase genes using operational taxonomic units (OTUs) was carried out after amplification and sequencing.

RESULTS

OTUs were 871 and 963 in the model group and control group, respectively, and 690 of these were identical. There were significant differences in Chao1 and ACE indices between the two groups (P < 0.05). Principal component analysis, principal coordination analysis and nonmetric multidimensional scaling analyses showed that OTUs distribution in the control group was relatively intensive, and differences among individuals were small, while in the model group, they were widely dispersed and more diversified. Bacterial lactase genes from the intestinal contents of the control group were related to Proteobacteria, Actinobacteria, Firmicutes and unclassified bacteria. Of these, Proteobacteria was the most abundant phylum. In contrast, the bacterial population was less diverse and abundant in the model group, as the abundance of Bradyrhizobium sp. BTAi1, Agrobacterium sp. H13-3, Acidovorax sp. KKS102, Azoarcus sp. KH32C and Aeromonas caviae was lower than that in the control group. In addition, of the known species, the control group and model group had their own unique genera, respectively.

CONCLUSION

Antibiotics reduce the diversity of bacterial lactase genes in the intestinal contents, decrease the abundance of lactase gene, change the lactase gene strains, and transform their structures.

Keywords: Antibiotics-induced diarrhea, Lactase genes, Gene diversity, Intestinal bacteria, High-throughput sequencing

Core tip: The mechanism of antibiotics-induced diarrhea has been studied in a wide range of diverse microbes, but less on functional enzymes. The current study aimed to determine the mechanism of lactase activity from genetic diversity and provide a basis for antibiotics-induced diarrhea. Alpha/Beta diversity analysis showed that there were significant differences between the control mice and model mice in types of lactase genes expressed and their activities. Following the antibiotics-induced diarrhea symptoms, the intestinal lactase genes changed, the number of strains was reduced and the abundance decreased, indicating changes in community structure and decreased diversity of lactase genes.