Megasphaera lornae sp. nov., Megasphaera hutchinsoni sp. nov., and Megasphaera vaginalis sp. nov.: novel bacteria isolated from the female genital tract

Abstract

Six strictly anaerobic Gram-negative bacteria representing three novel species were isolated from the female reproductive tract. The proposed type strains for each species were designated UPII 199-6T, KA00182T and BV3C16-1T. Phylogenetic analyses based on 16S rRNA gene sequencing indicated that the bacterial isolates were members of the genus Megasphaera . UPII 199-6T and KA00182T had 16S rRNA gene sequence identities of 99.9 % with 16S rRNA clone sequences previously amplified from the human vagina designated as Megasphaera type 1 and Megasphaera type 2, members of the human vaginal microbiota associated with bacterial vaginosis, preterm birth and HIV acquisition. UPII 199-6T exhibited sequence identities ranging from 92.9 to 93.6 % with validly named Megasphaera isolates and KA00182T had 16S rRNA gene sequence identities ranging from 92.6–94.2 %. BV3C16-1T was most closely related to Megasphaera cerevisiae with a 16S rRNA gene sequence identity of 95.4 %. Cells were coccoid or diplococcoid, non-motile and did not form spores. Genital tract isolates metabolized organic acids but were asaccharolytic. The isolates also metabolized amino acids. The DNA G+C content for the genome sequences of UPII 199-6T, KA00182T and BV3C16-1T were 46.4, 38.9 and 49.8 mol%, respectively. Digital DNA–DNA hybridization and average nucleotide identity between the genital tract isolates and other validly named Megasphaera species suggest that each isolate type represents a new species. The major fatty acid methyl esters include the following: C12 : 0, C16 : 0, C16 : 0 dimethyl acetal (DMA) and summed feature 5 (C15 : 0 DMA and/or C14 : 0 3-OH) in UPII 199-6T; C16 : 0 and C16 : 1 cis 9 in KA00182T; C12 : 0; C14 : 0 3-OH; and summed feature 5 in BV3C16-1T. The isolates produced butyrate, isobutyrate, and isovalerate but there were specific differences including production of formate and propionate. Together, these data indicate that UPII 199-6T, KA00182T and BV3C16-1T represent novel species within the genus Megasphaera . We propose the following names: Megasphaera lornae sp. nov. for UPII 199-6T representing the type strain of this species (=DSM 111201T=ATCC TSD-205T), Megasphaera hutchinsoni sp. nov. for KA00182T representing the type strain of this species (=DSM 111202T=ATCC TSD-206T) and Megasphaera vaginalis sp. nov. for BV3C16-1T representing the type strain of this species (=DSM 111203T=ATCC TSD-207T).

The vaginal microbiome in women of reproductive age with healthy weight versus overweight/obesity

“…Taxa identified as contributing to these differences were Coriobacteriaceae OTU27, Megasphaera OTU71_type1 (recently renamed Megasphaera lornae sp. nov) (28), Saccharibacteria TM7 OTUH1, Prevotellaceae OTU61, and Mobiluncus mulieris (Figure 3). The full heat map analysis is noted in Supporting Information Figure S1.…”

A specific structure and high richness characterize intestinal microbiota of HIV-exposed seronegative individuals

“…Recently, an increase in Succinivibrio and Megasphaera have been described in infected patients under antiretroviral therapy [ 40 ]. In addition, the Megasphaera genus has been found in high proportion in healthy vaginal microbiota, especially in the genital tract [ 41 ]. It is important to note that most HESN in this study were female, and their HIV-infected partners were on ART at sampling, which could explain the enrichment of these genera in HESN.…”

“…It is known that the production of favorable short-chain fatty acids (SCFA) by some bacteria has anti-inflammatory, antitumorigenic, and antimicrobial effects, maintaining gut integrity and immune homeostasis [ 42 ]. Interestingly, genera enriched in HESN such as Succinivibrio , Megasphaera , Butyrivibrio , and Victivallis are known SCFA-producers [ 41 – 44 ], suggesting a larger SFCA pool in HESN than HIV+ subjects. However, the relevance of these genera in HESNs remains to be fully described.…”

Unique roles of vaginal Megasphaera phylotypes in reproductive health

“…Unfortunately, our repeated attempts to recover the isolates from frozen stocks were not successful, and we were thus unable to perform biochemical assays. Since our initial submission, Srinivasan et al confirmed that none of the vaginal Megasphaera, including MP2, were able to use glucose as a carbon source [ 83 ].…”