Degradation of Chitin and Chitosan by a Recombinant Chitinase Derived from a Virulent Aeromonas hydrophila Isolated from Diseased Channel Catfish


A chitinase was identified in extracellular products of a virulent Aeromonas hydrophila isolated from diseased channel catfish (Ictalurus punctatus). Recombinant chitinase (rChi-Ah) was produced in Escherichia coli. Purified rChi-Ah had optimal activity at temperature of 42 and pH 6.5. The affinity (Km) for chitosan was 4.18 mg·ml-1 with Vmax of 202.5 mg·min-1·mg-1. With colloidal chitin as substrate, rChi-Ah generated N,N’-diacetyl-glucosamine predominantly. Conversion of chitosan (≥75% deacetylated) by rChi-Ah revealed five major products: 2 to 4 units of glucosamine, all of which had at least one acetyl group. It was determined that N-acetylated glucosamine was the recognition and cleavage site of rChi-Ah; the minimal and maximal cleavages were two and four glucosamine units, respectively. Functional analysis of rChi-Ah suggests that A. hydrophilachitinase is a bioactive chitinolytic enzyme, which may benefit the pathogen for survival and/or infection.

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Zhang, D. , Bland, J. , Xu, D. and Chung, S. (2015) Degradation of Chitin and Chitosan by a Recombinant Chitinase Derived from a Virulent Aeromonas hydrophila Isolated from Diseased Channel Catfish. Advances in Microbiology, 5, 611-619. doi: 10.4236/aim.2015.59064.

Conflicts of Interest

The authors declare no conflicts of interest.


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