Molecular ecological network analysis reveals the effects of probiotics and florfenicol on intestinal microbiota homeostasis: An example of sea cucumber

Gang Yang,Xiangli Tian,Shuanglin Dong,Mo Peng

doi:10.1038/s41598-017-05312-1

Abstract

Animal gut harbors diverse microbes that play crucial roles in the nutrition uptake, metabolism, and the regulation of host immune responses. The intestinal microbiota homeostasis is critical for health but poorly understood. Probiotics Paracoccus marcusii DB11 and Bacillus cereus G19, and antibiotics florfenicol did not significantly impact species richness and the diversity of intestinal microbiota of sea cucumber, in comparison with those in the control group by high-throughput sequencing. Molecular ecological network analysis indicated that P. marcusii DB11 supplementation may lead to sub-module integration and the formation of a large, new sub-module, and enhance species-species interactions and connecter and module hub numbers. B. cereus G19 supplementation decreased sub-module numbers, and increased the number of species-species interactions and module hubs. Sea cucumber treated with florfenicol were shown to have only one connecter and the lowest number of operational taxonomic units (OTUs) and species-species interactions within the ecological network. These results suggested that P. marcusii DB11 or B. cereus G19 may promote intestinal microbiota homeostasis by improving modularity, enhancing species-species interactions and increasing the number of connecters and/or module hubs within the network. In contrast, the use of florfenicol can lead to homeostatic collapse through the deterioration of the ecological network.

Highlights

The animal intestines harbor complex communities of microbes that are considered an integral component of the host organism[1]
A total of 2,720,976 high-quality sequences were generated by sequencing the V3–V4 region of the bacterial 16 S rDNA from intestinal content samples collected from the sea cucumber with dietary basal diet (Control) and supplementation with probiotics P. marcusii BD11 (PM) and B. cereus G19 (G19), and antibiotics florfenicol (FL), respectively
To assess the species richness and diversity of intestinal microbiota of sea cucumbers, the Chao[1] and abundance-based coverage estimator (AEC) and Shannon diversity were calculated by estimating the number of operational taxonomic units (OTUs)

Summary

Introduction

The animal intestines harbor complex communities of microbes that are considered an integral component of the host organism[1]. These microbial communities remain stable and are beneficial for the host health, as they are involved in the breakdown of complex molecules in food, protection from pathogens, and immune system development[2, 3]. The homeostasis of intestinal microbiota is considered critical for host health, the mechanisms underlying the stability of intestinal microbial communities are still elusive. Species-species interactions have not been reported, except in our previous study investigating sea cucumber (Apostichopus japonicus Selenka) microbiota[11]. The effects of these probiotics and an antibiotic on ecological networks within intestinal microbiota have not been reported previously

Methods

Results

Discussion

Conclusion