Seasonal Changes In Gut Microbiota Diversity In The Greater Horseshoe Bat

A large number of microorganisms colonize the intestines of animals.The gut microbiota plays an important role in nutrient metabolism and affects a number of physiological mechanisms in the host.Studies have shown that seasonal changes occur in the intestinal microbes of mammals that hibernate seasonally.However,these studies only focused on herbivores(e.g.,small rodents,such as Arctic ground squirrels,thirteen-line ground squirrels)and in carnivores(e.g.large mammals,such as brown bears).It remains unclear how hibernation affect the intestinal microbes of insectivores(e.g.bats).Rhinolophus ferrumequinum belongs to the Chiroptera,Rhinolophidae and Rhinolophus,and is a typical insectivorous species.The north population of R.ferrumequinum obligate hibernate during winter,and has become a typical species in the study of hibernating bats.In this study,we measured microbial diversity and composition in the gut of R.ferrumequinum in different periods(early spring,early summer,late summer,torpor,and interbout arousal)using 16 S ribosomal RNA gene amplicon sequencing.PICRUSt and metagenomic analyses were also used to investigate the function of bats' intestinal microorganisms.Follows are the main results:1.Five groups of four seasons of R.ferrumequinum(early spring,early summer,late summer,early winter torpor and early winter interbout arousals.).A total of 39 samples were performed 16 S ribosomal RNA gene amplicon sequencing.The bacteria detectedincluded 23 phylum,45 class,87 order,158 family,and 263 genus.We found seasonal changes in the diversity and composition of the gut microbes in R.ferrumequinum.The diversity of gut microbiota was highest in the late summer and lowest in the early summer.The relative abundance of Proteobacteria was highest in the early summer and significantly lower in other periods.The relative abundance of Firmicutes was lowest in the early summer and significantly increased in the late summer,followed by a significant decrease in the early winter and early spring.The relative abundance of Tenericutes was significantly higher in the early spring compared with other periods.2?The results of PICRUSt suggested that the relative abundance of most predicted functional categories changed significantly among the different groups,including metabolism of lipids,carbohydrates,amino acids,and energy.3?Metagenome sequencing was performed on 12 intestinal content samples of R.ferrumequinum from four periods(early spring,early summer,late summer,and early winter).The results of metagenomic analyses showed that gut microbes of R.ferrumequinum are involved in a series of metabolic pathways,including signal transduction,membrane transport,carbohydrates,amino acids,and energy metabolism,which were associated with a series of basic life functions,including metabolism,enzyme synthesis,DNA replication,recombination and repair.Moreover,the relative abundance of functional categories in each period was different.Overall,our results showed that seasonal physiological changes associated withhibernation altered the gut microbial community of R.ferrumequinum.Hibernation may also alter the metabolic function of intestinal microbes,improved adaptability of R.ferrumequinum to extreme winter conditions.This study enhanced our understanding about the symbiosis relationship between hibernating mammals and gut microbes.