Integrated metagenomic analysis of bacteriomes associated with beach-cast seaweeds reveals metabolic potential for biotechnological and environmental applications

Beach-cast seaweeds provide nutrient-rich microhabitats for distinct microbial assemblages, which represent an underexplored component of the coastal ecosystem. In this study, an integrated approach based on 16 S rRNA metabarcoding and shotgun metagenomics was employed for a genome-resolved investigation of the bacteriomes associated with the beach cast seaweeds from Goa, India. Community-level analyses revealed a diverse bacterial assemblage dominated by Pseudomonadota, Bacteroidota, Actinomycetota, and Cyanobacteriota, along with candidate phyla, including Saccharibacteria, Parcubacteria, SR1, and Latescibacteria, indicating the presence of uncharacterized microbial lineages. Functional profiling of the metagenomic community revealed representation of gene sequences associated with core metabolism, carbohydrate processing, stress adaptation, and xenobiotic-related functions. Carbohydrate-active enzyme annotations were dominated by glycosyltransferases; glycoside hydrolases, linked to α-glucan- and β-glucoside-related substrates and polysaccharide lyases targeting uronic-acid-containing polysaccharides. This suggests a strong genome-predicted capacity of the bacterial community for the biotransformation of macroalgal biomass. Genome-resolved metagenomic analysis recovered four metagenome-assembled genomes affiliated with Cyanobacteriota, Bacteroidota, Actinomycetota, and Chloroflexota. They encode taxon-specific metabolic repertoires related to organic matter transformation and gene sequences associated with sulfated polysaccharide turnover and xenobiotic-related oxidation pathways, including arylsulfatases, cytochrome P450 monooxygenases, and dehydrogenases. This functional overlap suggests that beach-cast seaweed-associated bacteria have the inherent capacity to act on chemically diverse organic substrates and xenobiotic compounds in coastal zones. These findings highlight the metabolic and functional diversity of beach-cast seaweed-associated microbiomes, underscoring their potential as genomic resources for biotechnological exploration and environmental applications.