Characterization of three bacterial glycoside hydrolase family 9 endoglucanases with different modular architectures isolated from a compost metagenome

Environmental bacteria express a wide diversity of glycoside hydrolases (GH). Screening and characterization GH from metagenomic sources provides an insight into biomass degradation strategies non-cultivated prokaryotes. In the present report, we screened compost metagenome for lignocellulolytic activities identified six genes encoding enzymes belonging to family GH9 (GH9a-f). Three these (GH9b, GH9d GH9e) were successfully expressed characterized. A phylogenetic analysis catalytic domain pro- eukaryotic suggested existence two major subgroups. Bacterial GH9s displayed variety modular architectures those harboring N-terminal Ig-like domain, such as GH9b GH9d, segregated remainder. We purified characterized endoglucanases both subgroups examined their stabilities, substrate specificities product profiles. GH9e exhibited original hydrolysis pattern, liberating elevated proportion oligosaccharides longer than cellobiose. All processive behavior synergistic action on crystalline cellulose. Synergy was also evidenced between GH48 enzyme same metagenome. The different distinct presence cellulose binding shown be necessary digestion insoluble cellulosic substrates, but not processivity. identification functional three members highlight importance this in bacterial deconstruction. • cellulases structures Phylogenetic revealed high structural enzymes. CBM2 CBM3 shows pattern. with CBM4 has similar activity amorphous cellulase evidenced.