Overview of predicted differential functions of the vaginal microbiota based on RNA-seq analysis. The predominant lactobacilli present in the healthy condition results in a relatively simple environment where carbohydrates are converted to lactic acid. This results in a low pH and inhibition of the growth of other anaerobic organisms. The more complex microbial composition in bacterial vaginosis (BV) results in an increase in cell lysis, and an increase in carbohydrate availability. In this case, the carbohydrates are converted to succinate and other short-chain fatty acids (SCFAs) that can modulate host immunity, increase the pH and increase the reducing environment. Concomitant with this is an increase in bacteriophage load, and the potential for several organisms to cooperate to produce the malodorous compounds found in some cases of BV.