Microorganisms living on macroalgae: diversity, interactions, and biotechnological applications

Marine microorganisms play key roles in every
marine ecological process, hence the growing interest in
studying their populations and functions. Microbial communities
on algae remain underexplored, however, despite their
huge biodiversity and the fact that they differ markedly from
those living freely in seawater. The study of this microbiota
and of its relationships with algal hosts should provide crucial
information for ecological investigations on algae and aquatic
ecosystems. Furthermore, because these microorganisms interact
with algae in multiple, complex ways, they constitute an
interesting source of novel bioactive compounds with biotechnological
potential, such as dehalogenases, antimicrobials,
and alga-specific polysaccharidases (e.g., agarases,
carrageenases, and alginate lyases). Here, to demonstrate the
huge potential of alga-associated organisms and their metabolites
in developing future biotechnological applications, we
first describe the immense diversity and density of these
microbial biofilms. We further describe their complex interactions
with algae, leading to the production of specific bioactive
compounds and hydrolytic enzymes of biotechnological
interest. We end with a glance at their potential use in
medical and industrial applications.