Bacterial Communities and Diversity of Western Ghats Soil: A Study of a Biodiversity Hotspot.

The Western Ghats is one of India's mega-diversity hotspots and an ecologically and geologically important area for the diversity of endemic plants and animals. The present study provides insights into the aerobic bacterial diversity and composition of the soils of North Western Ghats located in Maharashtra state (NWGM), India. The samples for the culture-dependent study were collected from 6 different locations namely Malshej Ghat, Bhimashankar, Lonavala, Mulshi, Tail-Baila, and Mahabaleshwar. A total of 173 isolates were obtained from the different samples, which belonged to Proteobacteria (43%), Firmicutes (36%), and Actinobacteria (19%). Sequences of 15 strains shared ≤ 98.7% similarity (a species cut-off) which represent potential novel species. Metagenomic analysis revealed the presence of Actinobacteria and Proteobacteria as the most dominant phyla at both MB and MG. However, both sites showed variation in the composition of rare phyla and other dominant phyla. This difference in bacterial community composition could be due to differences in altitude or other physicochemical properties. The functional prediction from the amplicon sequencing showed the abundance of carbohydrate, protein, and lipid metabolism which was corroborated by screening the isolated bacterial strains for the same. The present study has a unique take on microbial diversity and defines the importance of community assembly processes such as drift, dispersal, and selection. Such processes are relatively important in controlling community diversity, distribution, as well as succession. This study has shown that the microbial community of NWGM is a rich source of polysaccharide degrading bacteria having biotechnological potential.

Classification of uncultivated anammox bacteria and Candidatus Uabimicrobium into new classes and provisional nomenclature as Candidatus Brocadiia classis nov. and Candidatus Uabimicrobiia classis nov. of the phylum Planctomycetes and novel family Candidatus Scalinduaceae fam. nov to accommodate the genus Candidatus Scalindua.

The phylum Planctomycetes is metabolically unique group of bacteria divided in two classes Planctomycetia and Phycisphaerae. Anaerobic ammonia-oxidizing (anammox) bacteria are the uncultured representatives of the phylum Planctomycetes. Anammox bacterial genera are placed in the family Candidatus (Ca.) Brocadiaceae of the order Ca. Brocadiales, assigned to the class Planctomycetia. Phylogenetic analysis, showed that the anammox bacteria and Ca. Uabimicrobium form a divergent clade from the rest of the cultured representatives of the phylum Planctomycetes. The phylogenetic study, pairwise distance and Average Amino acid Identity (AAI) showed that anammox bacteria don't belong to the classes Planctomycetia and Phycisphaerae. Anammox bacteria and Ca. Uabimicrobium form a deep-branching third clade in the phylogenetic analysis indicating that it is the most ancient third class within the phylum Planctomycetes. Phenotypic characters also separate anammox bacteria from classes Planctomycetia and Phycisphaerae. Therefore, based on phenotypic, phylogenetic, pairwise distance, AAI and phylogenomic analysis we propose a novel class Ca. Brocadiia to accommodate the order Ca. Brocadiales of anammox bacteria except Ca. Anammoximicrobium. Genera Ca. Jettenia, Ca. Anammoxoglobus, Ca. Kuenenia and Ca. Brocadia show their phylogenetic affiliation to the family Ca. Brocadiaceae. However, Ca. Scalindua showed a distant relationship with the family Ca. Brocadiaceae. Therefore, we suggest the exclusion of the genus Ca. Scalindua from the family Ca. Brocadiaceae; and propose its inclusion under a novel family with a provisional name as Ca. Scalinduaceae fam. nov. Similarly, Ca. Uabimicrobium amporphum showed distinct phylogenetic affiliation, therefore we propose a novel class Ca. Uabimicrobiia classis nov. to accommodate the genus Ca. Uabimicrobium.