Vaginal microbe media (VMM): a novel medium to culture Lactobacillus iners and other fastidious vaginal bacteria

A more comprehensive understanding of the bacterial species in the vaginal microbiome and their roles requires their cultivation as pure isolates. However, difficulty in culturing fastidious species, particularly in liquid media, has limited certain types of experimental approaches for studying these organisms. To address this challenge, Vaginal Microbe Medium (VMM) was developed to enable robust growth of Lactobacillus iners within a relatively short period (36 h). A simplified version with fewer components, named VMM2, was subsequently developed. L. iners strains grown in VMM and VMM2 reached higher optical densities in a shorter period compared to NYCIII, supplemented MRS and Columbia broth. Bacterial cells cultured in VMM and VMM2 were significantly longer than those grown in NYCIII. These results indicate that VMM and VMM2 provide superior growth conditions for L. iners as compared to currently available media. Both media also support the growth of a range of other vaginal bacterial species. The development of these media facilitates liquid culture of fastidious bacteria from the vaginal niche, enabling broader experimental capabilities and deeper insights into causal relationships within the microbiome.