Signatures of vaginal microbiota by 16S rRNA gene: potential bio-geographical application in Chinese Han from three regions of China

The human microbiome is expected to be a new and promising tool for classification of human epithelial materials. Vaginal fluids are one of the most common biological samples in forensic sexual assault cases, and its identification is crucial to accurately determine the nature of the case. With the development of molecular biology technologies, the concept of vaginal microflora in different physiological states, ethnic groups, and geography is constantly improved. In this study, we conducted high-throughput sequencing of the V3–V4 hypervariable regions of the 16S rRNA gene in vaginal samples from Henan, Guangdong, and Xinjiang populations, in an attempt to reveal more information about the vaginal microflora in different regions. The results showed that the bio-geographical factors might affect the relative abundance of some vaginal microflora, but there was no significant difference in the composition of dominant bacteria in the vagina, which was mainly composed of Lactobacillus and Gardnerella. However, prediction models based on the random forest algorithm suggested that we might be able to distinguish vaginal fluids from populations of different regions according to the species-level OTUs in low abundance. It is promising that microbiome-based methods could provide more personal information when being attempted to trace the origin of body fluids.