Amplification of the V5 - V8 region of the 16S rRNA gene effectively speciates medically important genital tract Lactobacillus species in the upper female genital tract

Abstract

BackgroundThe endometrial cavity is an upper genital tract site largely heralded as sterile, however, advances in culture-independent, next generation sequencing technology have revealed that this site harbours a rich microbial community which includes multiple Lactobacillus species. These bacteria are considered to be the most common non-pathogenic genital tract commensals. Next-generation sequencing of the female lower genital tract has revealed significant variation amongst microbial community composition with respect to Lactobacillus sp. in samples collected from healthy and diseased women. The aim of this study was to evaluate the ability of the 16S rRNA gene to characterize genital tract lactobacilli to species-level taxonomy.\n\nMethodsSamples were interrogated for the presence of microbial DNA using two-step next generation sequencing technology to exploit the V5-V8 regions of the 16S rRNA gene and compared to standard speciation using qPCR.\n\nResultsThe V5-V8 region of the 16S rRNA gene has sufficient sequence variation within frequently encountered genital tract lactobacilli to allow accurate determination of relative abundance within the community, and speciation for several key community members without completing additional experimentation.\n\nConclusionsNext-generation sequencing of clinical genital tract isolates is an effective method for high throughput identification to species-level of key Lactobacillus sp.\n\nIMPORTANCEHuman microbiome experiments, including the low biomass organs such as the upper genital tract, require the development of consensus protocols to ensure accurate comparison between such studies and our data forms an important foundation for future protocols.\n\nThis paper provides evidence to support the selection of the V5-V8 regions of the 16S rRNA gene improved Lactobacillus speciation using next generation sequencing technology. The choice of variable region for broad-range amplification in microbiome studies is important due to preferential primer binding associated with some genera based on nucleotide sequence patterns. By utilising the V5-V8 region, multiple species of Lactobacillus can be characterised with relative confidence.