Studying the great potential of cultivable bacteria associated with the brown alga Ascophyllum nodosum

Bacteria associated with algae differ markedly from those living freely in seawater and represent great potential for the production of diverse bioactive compounds as they interact in multiple complex ways with their host. Here we identified new bacterial species, and their polysaccharolytic activities, associated with the brown alga Ascophyllum nodosum.
To isolate cultivable microorganisms, algal thalli of Ascophyllum nodosum were swabbed with sterile cotton tips and marine agar plates were inoculated. Three-hundred isolated bacteria were screened for agarase, kappa- or iota-carrageenase activities on specific marine media. Thirty-two bacteria with polysaccharolytic activities were isolated and a part of their 16S rDNA (8F-1492R) were amplified and sequenced. Twenty-seven were classified as Flavobacteriia and five as Gammaproteobacteria. Putative new strains and species of Zobellia, Maribacter, Cellulophaga, Shewanella, Glaciecola, Pseudoalteromonas and Colwellia were identified by phylogenetic analysis. Genomics libraries with their DNA were constructed in Escherichia coli and Bacillus subtilis and are currently screened for diverse enzymatic activities (agarases, iota-and kappa-carrageenases, cellulases, beta-glucosidases, sulfatases and amylases).
In an era where high throughput sequencing is mostly used to study bacterial communities, cultivation methods are underestimated. Here, we revealed that only ten percent of the cultivable bacteria on this brown alga could degrade algal polysaccharides, which lead to asking us; who and what are the 90 other percents doing there? Furthermore, by this cultivation method we could also identify putative new bacterial strains/species, which are screened for polysaccharidases. Novel glycoside hydrolases from unknown marine bacteria represent great biotechnological potential as they should have original industrial properties.