Discovery of a novel marine Bacteroidetes with a rich repertoire of carbohydrate-active enzymes

• Published in: Computational and structural biotechnology journal 2024-12, Vol.23, p.406-416
• Main Authors: Chen, Beihan, Liu, Guohua, Chen, Quanrui, Wang, Huanyu, Liu, Le, Tang, Kai
• Format: Article
• Language: English
• Subjects: Bacteroidetes; Carbohydrate-active enzymes; Comparative genomic analysis; Polysaccharide metabolism; Type IX secretion system
• ISSN: 2001-0370; 2001-0370
• DOI: 10.1016/j.csbj.2023.12.025

Members of the phylum Bacteroidetes play a key role in the marine carbon cycle through their degradation of polysaccharides via carbohydrate-active enzymes (CAZymes) and polysaccharide utilization loci (PULs). The discovery of novel CAZymes and PULs is important for our understanding of the marine carbon cycle. In this study, we isolated and identified a potential new genus of the family Catalimonadaceae, in the phylum Bacteroidetes, from the southwest Indian Ocean. Strain TK19036, the type strain of the new genus, is predicted to encode CAZymes that are relatively abundant in marine Bacteroidetes genomes. NBRC 107804 , NBRC 107748 and NBRC 109829 , which exhibit 16 S rRNA similarities exceeding 90% with strain TK19036, and belong to the same family, were selected as reference strains. These organisms possess a highly diverse repertoire of CAZymes and PULs, which may enable them to degrade a wide range of polysaccharides, especially pectin and alginate. In addition, some secretory CAZymes in strain TK19036 and its relatives were predicted to be transported by type IX secretion system (T9SS). Further, to the best of our knowledge, we propose the first reported "hybrid" PUL targeting alginates in NBRC 107804 . Our findings provide new insights into the polysaccharide degradation capacity of marine Bacteroidetes, and suggest that T9SS may play a more important role in this process than previously believed.