Macroalgal Epiphytic Microbiome: A Potential Source of Novel Drugs

In the marine rocky intertidal ecosystem, macroalgae (seaweeds) serve ecosystem engineers that create, modify, or maintain the physical habitat for their own and other species. Intriguingly, most marine macroalgal species evolved with microbial colonization and biofilm formation on their surface. The macroalgae (basibiont) and associated epiphytic microbiota (epibiont) act as a functional unit known as a “macroalgal holobiont,” characterized by its complex chemical interactions. In this non-trophic association, the epiphytic microbial biofilm forms a protective layer essential in host defense against foulers, consumers, or pathogens. In addition, antimicrobial activity is widespread among these epiphytic microbes. However, due to their thinness and often negligible biomass, the chemo-ecological impact of this epiphytic microbiome is severely underestimated. This chapter aims to review the antimicrobial potential of the “macroalgal epiphytic microbiome” and introduce the application of “meta-omics” approaches for further exhaustive exploitations of this unique microbiome for future drug discovery.