Comprehensive Analysis of Salt-Tolerant Extremophilic Bacterial Groups in the Coastal Belt of Digha, India

The saline coastal regions of Digha, West Bengal, India, present extreme environments that support diverse microbial communities with significant ecological and industrial potential. This study aimed to investigate the population dynamics of soil bacteria, perform metagenomic profiling, and analyze key physicochemical parameters. Soil samples from coastal sites were analyzed using V3–V4 amplicon sequencing of the <i>16S rRNA</i> gene on the Illumina MiSeq platform. The dominant bacterial phyla included <i>Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Bacteroidetes</i> and others. We quantified several functional bacterial groups - heterotrophic, spore-forming, phosphate-solubilizing, denitrifying, nitrogen-fixing, nitrate-reducing, starch-hydrolyzing, lipid-hydrolyzing, and Gram-negative bacteria with populations ranging from 6.872 to 6.442 × 10⁶, 7.776 to 7.05 × 10⁵, 6.256 to 4.873 × 10³, 5.253 to 4.753 × 10³, 1.233 to 0.61 × 10³, 1.353 to 0.8433 × 10³, 3.813 to 3.436 × 10³, 3.886 to 2.846 × 10², and 4.596 to 3.763 × 10³ CFU/g dry soil. Seasonal environmental parameters such as temperature, pH, salinity, organic carbon, nitrate, phosphate, dissolved oxygen, and soil texture were also recorded. An artificial neural network (ANN) model identified temperature and salinity as the most influential factors affecting bacterial populations. This study offers preliminary insight into the structure and environmental drivers of coastal soil microbiomes in Digha and emphasizes the need for further research into their functional roles and adaptive mechanisms.