Representatives of Melioribacteraceae Are the Source of Glycoside Hydrolases from Under-Explored Families and Families with Various Activities

Members of the family Melioribacteraceae are thermophilic facultatively anaerobic polysaccharide-degrading bacteria. Here we report results of genome analysis of all cultivated Melioribacteraceae (Melioribacter roseus, Stygiobacter electus, Rosettibacter primus, R. firmus, and Pyranulibacter aquaticus) focused on glycoside hydrolases belonging to the families with low number of characterized enzymes (GH105, GH147, GH148, GH165, and GH175) and the families containing enzymes possessing various activities (GH5, GH9, GH16, GH43, GH51, and others). Phylogenetic analysis of glycoside hydrolases revealed that some of them (GH9, GH16, GH39, GH43, and GH51) form clades distant from the characterized homologues. In addition to catalytic domains, many analyzed proteins contain in their structure domains associated with substrate binding and adhesion, such as different CBM, immunoglobulin-like, and concanavaline-like domains. These enzymes may possess novel properties which can be promising for both fundamental science and industry.