Abstract
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.