Genome-based identification of heavy metal resistance-associated genes in Bacillus enclensis ABF750 isolated from the polluted sediment of Versova Creek.

Heavy metal pollution is a major environmental concern in coastal ecosystems, particularly in urban estuarine systems where anthropogenic activities lead to the accumulation of toxic metals in sediments and water bodies. The urgent need to identify microorganisms capable of tolerating and remediating heavy metal contamination has driven interest in environmentally adapted bacterial strains. In the present study, a bacterial strain, Bacillus enclensis ABF750, was isolated from sediment collected from the highly polluted Versova Creek, Mumbai, India, and its adaptive potential was investigated using whole-genome phylogenetic analysis and functional genome annotation. Genomic analysis revealed the presence of numerous heavy metal resistance determinants, including genes involved in metal sensing, detoxification, transport, and efflux mechanisms, along with siderophore-associated biosynthetic pathways that contribute to metal chelation and stress tolerance. Sediment analysis confirmed multi-metal contamination, while water quality measurements indicated extreme environmental conditions characterized by persistent anoxia (0 mg/L dissolved oxygen), high biological oxygen demand (28.51-41.18 mg/L), and elevated ammonium (186.74-243.3 µmol/L) and phosphate (25.4-29.63 µmol/L) concentrations. These physicochemical conditions demonstrate the highly stressed nature of the habitat and highlight the remarkable adaptability of B. enclensis ABF750 to nutrient toxicity, salinity fluctuations, and metal stress. Collectively, these findings demonstrate that Versova Creek represents a severely stressed and anthropogenically impacted estuarine habitat characterized by persistent anoxia, nutrient enrichment, and multi-metal contamination with promising potential for bioremediation of metal-contaminated coastal ecosystems.