Diversity of glycosidase activities in the bacteria of the phylum Bacteroidetes isolated from marine algae

Glycosidase activities of 177 strains of the phylum Bacteroidetes, belonging to 18 genera and isolated from the algae Chondrus sp., Polysiphonia sp., Neosiphonia japonica, Saccharina crassifolia, Saccharina japonica, Chorda filum, Acrosiphonia sonderi, and Ulva fenestrata collected in the littoral zones of the Sea of Okhotsk and the Sea of Japan, Pacific Ocean, were studied. According to the data obtained, glycosidases catalyzing hydrolysis of the beta-glycoside bond were present in over 70% epiphytes of marine algae. It should be noted that alpha-galactosidases and the extremely rare enzymes, alpha-N-acetylgalactosaminidases, were more frequent in the Bacteroidetes than in the proteobacteria analyzed previously. It was found that the overwhelming majority of the bacteria of the dominant genera Zobellia and Maribacter contained the complete set of the tested glycosidases involved in degradation of algal polysaccharides. Apparently, the presence of the wide range of glycosidases in bacterial strains of these genera makes it possible for them to occupy diverse ecological niches under extreme conditions of the tidal zone. However, such important enzymes of the microbial lytic complex as alpha-galactosidases, beta-galactosidases, or beta-xylosidases, were not detected in the numerically important genus Winogradskyella. The noted difference in the metabolic profiles of the strains of these genera suggests the assumption that Winogradskyella strains play an unique role in the microbial communities, unrelated to the hydrolysis of such polysaccharides as agar and carrageenan. Significant differences in production of glycosidases among the different taxonomic groups were revealed, which is of importance for directed search of promising enzymes for biotechnology.