Background Lactobacilli are gatekeepers of vaginal ecosystem impeding growth of pathogenic microbes and their diversity varies across populations worldwide. The present study investigated diversity of human vaginal microbiota among females of Northeast India, who are distinct in dietary habits, lifestyle, and genomic composition from rest of India. Results Altogether, 154 bacterial isolates were obtained from vaginal swab samples of 40 pregnant and 29 non-pregnant females. The samples were sequenced for 16 s rRNA gene and analysed for identification using a dual approach of homology search and maximum likelihood based clustering. Molecular identification based on 16S rRNA gene sequence confirmed the isolates belonging to 31 species. Lactobacilli constituted 37.7% of the bacterial isolates with 10 species and other Lactic Acid Bacteria (39.61%) represented another 10 species, some of which are opportunistic pathogens. The remaining of the communities are mostly dominated by species of Staphylococcus (14.28%) and rarely by Propionibacterium avidum (3.90%) , Bacillus subtilis, Escherchia coli, Janthinobacterium lividum, and Kocuria kristinae (each 0.64%). Interestingly Lactobacillus mucosae and Enterococcus faecalis, which are globally uncommon vaginal microbes is found dominant among women of Northeast India. This tentatively reflects adaptability of particular Lactobacillus species, in distinct population, to better compete for receptors and nutrients in vaginal epithelium than other species. Further, intrageneric 16S rRNA gene exchange was observed among Enterococcus, Staphylococcus , and two species of Lactobacillus , and deep intraspecies divergence among L. mucosae, which pinpointed possibility of emergence of new strains with evolved functionality. Lactobacilli percentage decreased from young pregnant to aged non-pregnant women with maximum colonization in trimester II. Conclusion The study highlighted importance of assessment of vaginal microbiota, Lactobacillus in particular, across different population to gain more insight on female health. Electronic supplementary material The online version of this article (10.1186/s12866-019-1568-6) contains supplementary material, which is available to authorized users.

About half of the global methane (CH ) emission is contributed by the methanogenic archaeal communities leading to a significant increase in global warming. This unprecedented situation has increased the ever growing necessity of evaluating the control measures for limiting CH emission to the atmosphere. Unfortunately, research endeavors on the diversity and functional interactions of methanogens are not extensive till date. We anticipate that the study of the diversity of methanogenic community is paramount for understanding the metabolic processes in freshwater lake ecosystems. Although there are several disadvantages of conventional culture-based methods for determining the diversity of methanogenic archaeal communities, in order to understand their ecological roles in natural environments it is required to culture the microbes. Recently different molecular techniques have been developed for determining the structure of methanogenic archaeal communities thriving in freshwater lake ecosystem. The two gene based cloning techniques required for this purpose are 16S rRNA and methyl coenzyme M reductase (mcrA) in addition to the recently developed metagenomics approaches and high throughput next generation sequencing efforts. This review discusses the various methods of culture-dependent and -independent measures of determining the diversity of methanogen communities in lake sediments in lieu of the different molecular approaches and inter-relationships of diversity of methanogenic archaea.

The vaginal microbial composition of wellbeing women were predominated by Lactobacillus group which play prime character in health-promoting activities including the prevention of the colonization of pathogenic microbe. The present study focused to characterize the probiotic and cytotoxicity potential of the Lactobacillus strains collected from the vaginal environment of the healthy women. Lactobacillus strains were identified via biochemical characterization and 16SrRNA gene sequencing. Strains were also evaluated for their probiotic potentials that includes antibiotics sensitivity; survivability to gastrointestinal conditions; antibacterial activities, biofilm production, auto aggregation and adhesion abilities to hydrocarbon. Cytotoxic activities were assessed through 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay using HeLa (cervical), AGS (gastric cancer) and A549 (lung cancer) cell lines. Results identified five bacterial strains viz., (Lactobacillus mucosae K76, L. fermentum K81, L. fermentum K85, L. reuteri K97 and L. reuteri K99) contains high probiotic potential and three strains with high cytotoxic activities against cancer cell lines can be further explodes for the human beneficial activities. Finding from this study also indicates that vaginal environment represents a novel source of probiotic candidates.

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