Impact of anthropogenic organic matter on bacterial community distribution in the continental shelf sediments of southeastern Arabian Sea

The objective of this study was to understand the influence of anthropogenic organic matter on the spatial distribution microbial community in the continental shelf sediments of the Southeastern Arabian Sea (SEAS). The sediment samples were taken from the inner shelf (30 m depths) and outer shelf (100–200 m). The C:Nmolar ratio of the sediment displayed a significant variation between the inner and outer shelf and a higher terrestrial organic input in the inner shelf. Microbial community composition also showed a significant variation between the inner and outer shelf (p ≤ 0.05). Proteobacteria was the dominant phylum in the outer shelf sediments (42.5%), whereas Desulfobacterota (21.9%) was the dominant phylum in the inner shelf. Complex terrestrial organic matter degrading bacteria dominated the inner shelf, whereas oligophilic microbial community and autochthonous organic matter utilizing bacteria dominated the outer shelf. Thus the source of organic matter controlled the microbial distribution in the SEAS. •Significant variation in microbial community between inner and outer shelf sediments•Higher terrestrial organic input in the inner shelf sediments than the outer shelf•Source of organic matter controlled the microbial distribution•Proteobacteria dominated in outer shelf, whereas Desulfobacterota in the inner shelf