Comparative genome analysis provides novel insight into the interaction of Aquimarina sp. AD1, BL5 and AD10 with their macroalgal host

Comparative genomics reveals complex natural product biosynthesis capacities and carbon metabolism across host‐associated and free‐living Aquimarina (Bacteroidetes, Flavobacteriaceae) species

“…Hudson et al . () have recently provided a mechanistic understanding of the carbohydrate degradation capacities of strains AD1, AD10 and BL5 and the likely roles of carbon metabolism in the association with their algal host. Here, we reveal that the ability to degrade major compounds usually present in the cell wall of, or exuded by, ubiquitous marine hosts such as phytoplankton/algae/ and zooplankton/crustaceans, or present in marine snow, recently‐lysed cells, detritus or excretions of live organisms, is a common attribute of the Aquimarina genus being shared by all species and strains inspected so far.…”

“…Among the shared functions, noteworthy was the presence of several glycoside hydrolase (GH) families in the core Aquimarina genome, highlighting their likely importance as major mediators of carbon cycling in the oceans. This is consistent with accumulating, genome‐based evidence for a primary role of marine Bacteroidetes in the breakdown of high molecular weight biopolymers, particularly in surface‐dense microhabitats (Fernández‐Gómez et al ., ; Hudson et al ., ). Hudson et al .…”

“…This finding indicated possible cytotoxic capacities for an otherwise unsuspected bacterial taxon given its placement in the Bacteroidetes phylum, most renowned for its role in carbon cycling and whose genomes had been considered to present low numbers of PKS and non‐ribosomal peptide synthetase (NRPS)‐encoding genes (Donadio et al ., ). In recent years, the presence of such genes is being consistently detected in different Aquimarina strains via genome sequencing (Keller‐Costa et al ., ; Ranson et al ., ; Hudson et al ., ). Moreover, structure elucidation of cuniculene, the first trans ‐AT polyketide ever reported from Aquimarina , has just been achieved (Helfrich et al ., ).…”

“…These strains are also able to degrade crude chitin, which is thought to be directly correlated with the disease (Chistoserdov et al ., ). In fact, chitinase‐encoding genes or chitin degradation ability have already been reported for various Aquimarina species (Donadio et al ., ; Hudson et al ., ). Thus, chitin breakdown may be a key feature to better understand the ecology of these organisms as it bears relevance not only for their potential opportunistic behaviour but also for biogeochemical cycling in the oceans.…”

“…In line with this observation, Aquimarina strains AD1 and BL5 have been identified by Kumar et al (2016b) as etiological agents of bleaching in the red alga Delisea pulchra. Their broad polysaccharide degradation profile has been suggested as a pivotal feature in their opportunistic interaction with the host (Hudson et al, 2019).…”