Characterization of β-N-acetylglucosaminidase from a marine Pseudoalteromonas sp. for application in N-acetyl-glucosamine production

Abstract

The psychrotolerant Pseudoalteromonas issachenkonii PAMC 22718 was isolated for its high exo-acting chitinase activity in the Kara Sea, Arctic. An exo-acting chitinase (W-Chi22718) was homogeneously purified from the culture supernatant of PAMC 22718 and the molecular weight of W-Chi22718 was estimated to be ~112 kDa. Because of its β-N-acetylglucosaminidase activity, W-Chi22718 was able to produce N-acetyl-D-glucosamine monomers from chitin oligosaccharide substrates. W-Chi22718 displayed chitinase activity from 0？37 °C (optimal temperature of 30 °C) and maintained activity between pH 6.0 and 9.0 (optimal pH of 7.6). W-Chi22718 exhibited a relative activity of 13 and 35% of the maximal activity at 0 and 10 °C, respectively, which is comparable to the activities of previously characterized, cold-adapted, bacterial chitinases. W-Chi22718 activity was enhanced by K+, Ca2+, and Fe2+, but inhibited by Cu2+and sodium dodecyl sulfate. We found that W-Chi22718 can produce large amounts of N-acetyl-D-glucosamines from colloidal chitin when combined with the previously characterized cold-active endochitinase W-Chi21702. Genome sequencing revealed that the corresponding gene (chi22718_IV) is 2,856 bp and encodes a 951 amino acid protein with a calculated molecular weight of ~102 kDa.