Seaweed-associated epiphytic bacteria: Diversity, ecological and economic implications

The microbial communities associated with seaweeds remain underexplored, despite their enormous biodiversity and the fact that they differ significantly from their free-living marinecounterpart. Studying the epiphytic bacterial microbiota, directly or indirectly, plays a vital role in normal algal morphological development, metabolism, growth and defence against fouling organisms. Furthermore, as these bacteria interact with algae in multifaceted ways, they constitute a fascinating source of new bioactive compounds with antimicrobials, antibiotic potential and produce algal-specific polysaccharidases with biotechnological applications. Microscopy, accompanied by bacterial culture and molecular biology, has made it feasible to establish and identify the phylogenetic origin of various algae-associated bacterial communities. Thus, this review first highlights the immense diversity of the epiphytic bacteria associated with algae, predominantly from the phyla Proteobacteria, Bacteroidetes, and Firmicutes. We further describe the factors affecting the composition and abundance of the epiphytic bacteria and their ecological role. We end with the bioprospecting value of this interaction, such as the production of hydrolytic enzymes and specific bioactive compounds. However, further investigation of the epiphytic bacterial communities present in different macroalgae using new technologies is still needed, mainly to evaluate the production of various metabolites with biotechnologicalapplications.