Transcriptomic analysis of bacterial vaginosis-associated bacteria living in single or multispecies biofilms

Bacterial vaginosis (BV) is the most common cause of vaginal discharge among women worldwide. BV is characterized by an imbalance in the vaginal microbiota with depletion of protective Lactobacillus species and overgrowth of facultative and strictly anaerobic bacteria. Although the development of a polymicrobial biofilm on the vaginal epithelium is a hallmark of BV, interactions between key BV-associated bacteria (BVAB) [i.e. Gardnerella vaginalis, Fannyhessea vaginae, and Prevotella bivia] present in the biofilm are still not completely understood. In this study, we aimed to analyse the transcriptome of single and triple-species biofilms growing in the rich medium, New York City III (NYCIII). A previous analysis of triple-species biofilms composition by qPCR showed that the biofilms were mainly composed of G. vaginalis, followed by F. vaginae and P. bivia. The transcriptomic analysis revealed a total of 431 (34 upregulated and 397 downregulated), 126 (36 upregulated and 90 downregulated), and 39 (31 upregulated and 8 downregulated) differentially expressed genes for G. vaginalis, F. vaginae, and P. bivia, respectively. Gene ontology only detected enrichment for the downregulated genes of G. vaginalis and 47 GO terms were associated with molecular functions, cellular components and biological processes, mainly metabolism. Hence, this work showed the adaptation of 3 BVAB when growing in a triple-species biofilm, with several genes being differentially expressed in all the species growing in a polymicrobial biofilm. Overall design: To study the alterations that growing in single or in multispecies biofilms may have on bacterial vaginosis-associated bacteria, G. vaginalis, F. vaginae and P. bivia were grown both in single and triple-species biofilms and their transcriptomes were characterised.