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J Ind Microbiol Biotechnol (2005) 32: 1923 DOI 10.1007/s10295-004-0197-7
ORIGINAL PAPER
R. V. S. Amorim W. M. Ledingham K. FukushimaG. M. Campos-Takaki
Screening of chitin deacetylase from Mucoralean strains (Zygomycetes) and its relationship to cell growth rate
Received: 19 May 2004 / Accepted: 31 October 2004 / Published online: 25 January 2005 Society for Industrial Microbiology 2005
Abstract Chitin deacetylase (CDA) is an enzyme that catalyzes the hydrolysis of acetamine groups of N-acetyl-
D-glucosamine in chitin, converting it to chitosan in fungal cell walls. In the present study, the activity in batch culture of CDA from six Mucoralean strains, two of them wild type, isolated from dung of herbivores of Northeast Brazil, was screened. Among the strains tested, Cunninghamella bertholletiae IFM 46114 showed a high intracellular enzyme activity of 0.075 U/mg protein after 5 days of culture, and a wild-type strain of Mucor circinelloides showed a high intracellular enzyme activity of 0.060 U/mg protein, with only 2 days of culture, using N-acetylchitopentaose as substrate. This enzyme showed optimal activity at pH 4.5 in 25 mM glutamate-sodium buer at 50 C, and was stable over 1 h preincubation at the same temperature. The kinetic parameters of CDA did not follow Michaelis-Menten kinetics, but rather Hill anity distribution, showing probable allosteric behavior. The apparent KHILL and
Vmax of CDA were 28834 nmol/l and 0.080.01
U mg protein 1 min 1, respectively, using N-acetylchitopentaose as substrate at pH 4.5 at 50 C.
Keywords Chitin deacetylase Chitosan Cunninghamella bertholletiae Mucor circinelloides Zygomycetes
Introduction
Chitin deacetylase (CDA; E.C. 3.5.1.41) is an enzyme that catalyzes the hydrolysis of acetamine groups of N-acetylglucosamine in chitin, promoting the conversion to chitosan. This enzyme was rst identied and partially puried from extracts of Mucor rouxii [5], and has been puried and characterized from other Zygomycetes strains, such as Absidia coerulea [11], and from Aspergillus nidulans and Colletotrichum lindemuthianum [1, 16]. Enzymes of this type have been reported to occur in some insect species [6]. These enzymes are glycoproteins secreted either into the periplasmic region or into the culture medium and exhibit remarkable thermal stability and specicity for water-soluble b-(1,4)-linked
N-acetyl-D-glucosamine polymers. However, they vary considerably in their molecular weight and carbohydrate content 17].
In Zygomycetes, CDA has an important role in fungal growth, being...