Vaginal microbiome analysis of buffalo (Bubalus bubalis) during estrous cycle using high-throughput amplicon sequence of 16S rRNA gene

Animal hosts and the microbiota that symbiotically inhabit them benefit each other reciprocally. The microbiota potentially benefit from their animal hosts by increasing the microbial communities through communication signals. Recent investigations reveal novel and important connections between microbiota of an animal and the latter's social behavior. It has been proposed that i) the bacteria produce odorous metabolites for their hosts for purpose of communication and ii) variation in chemical signals of the host is a product of variation in the inhabiting bacterial communities. Though the vaginal microbiome contributes greatly to aspects of reproduction in cattle, including producing odor, there is only a very limited knowledge about the composition of the microbiome during various phases of the estrous cycle. Hence, the present study was undertaken to evaluate and compare microbial diversity in the vagina of buffalo during various phases of the estrous cycle by adopting high throughput sequencing methods. Microbes belonging to Proteobacteria (98.19%), Actinobacteria (1.28%), Firmicutes (0.34%), and Bacteroidetes (0.18%) were present during the pre-estrus phase. Those belonging to Proteobacteria (40.22%), Firmicutes (26.17%), Actinobacteria (18.66%), Bacteroidetes (13.29%), and Tenericutes (0.03%) were present during the estrus phase. During the di-estrus phase, Proteobacteria (85.22%), Actinobacteria (5.89%), Firmicutes (3.82%), Bacteroidetes (0.21%), and Tenericutes (4.7%) were present. Our data provide evidence for diversity of vaginal microbiota, which may be greatly influenced by the host's physiology. The increased abundance of unassigned taxa in the vagina may play a significant biological role in the estrous cycle of the host. The study also revealed that the bacteria inhabiting buffalo vagina are distinct during different phases of the estrous cycle. It is suggested that the physiological and biochemical processes that occur in the vagina during the various phases of estrous cycle could play significant roles in determining the microbial composition, and provide vital information about microbial community structure in the buffalo vagina during the estrous cycle. Knowledge about the vaginal microbiota would contribute to improved management of buffalo reproduction.