TITLE:
Degradation of Chitin and Chitosan by a Recombinant Chitinase Derived from a Virulent Aeromonas hydrophila Isolated from Diseased Channel Catfish
AUTHORS:
Dunhua Zhang, John M. Bland, Dehai Xu, Siyin Chung
KEYWORDS:
Aeromonas hydrophila, Recombinant Chitinase, Chitin Degradation, Chitosan Degradation
JOURNAL NAME:
Advances in Microbiology,
Vol.5 No.9,
August
26,
2015
ABSTRACT: A chitinase was identified in extracellular products of a virulentAeromonas hydrophilaisolated from diseased channel catfish (Ictalurus punctatus). Recombinant chitinase
(rChi-Ah) was produced inEscherichia 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-1withVmaxof 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 thatA.
hydrophilachitinase is a bioactive
chitinolytic enzyme, which may benefit the pathogen for survival and/or
infection.