Billgrantia sp. NRB1 Genome sequencing
Lonar lake (India), a saline soda crater lake formed on basaltic rocks by a meteorite impact, hosts diverse but underexplored microbial communities. This study reports a novel haloalkaliphilic nitrate-reducing bacterium, Billgrantia alkalidenitrificans NRB1 from lakes sub-surface sediments. NRB1 strain, characterized as a gram negative, facultative anaerobe, displays remarkable adaptability to a wide range of salinities, temperatures, and pH levels. Phylogenetic analysis using 16S rRNA, orthologous genes and whole-genome revealed that NRB1 clustered closely with Billgrantia campisalis 4A. The genome-to-genome distance (34.30%), average nucleotide identity (87.93%), and average amino acid identity (89.76%) between NRB1 and B. campisalis 4A are lower than the threshold values required for the demarcation of a novel species. Distinguished by its oxidase, catalase, and urease activities, it exhibits distinct substrate utilization patterns and is also capable of reducing oxygen, nitrate and nitrite. The genome consists of a complete set of denitrification, sulphide oxidation, sugar metabolism, and reductive glycine pathway genes, indicating pivotal role in the biogeochemical cycling of various elements like nitrogen, sulphur, oxygen, and carbon. It also harbors partial iron metabolism genes. This study expands the limited knowledge on haloalkaliphilic extremophiles by reporting a new bacterial species, Billgrantia alkalidenitrificans NRB1, along with its unique physiological and metabolic traits under haloalkaline environments. It advances the understanding of the ecology and diversity of microorganisms inhabiting extremophilic environments and provides insights on the genomic analysis across the Billgrantia genus through comparative phylogenetic, pangenomic, and metabolic/gene signatures and their profiling, while also contributing to the recent taxonomic classification of the genus Billgrantia.
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