In the isolation of 67 isolates, obtained from 25 sample of fruits and lookpangs, 18 stains of fungi were found to produce chitin deacetylase. All isolates were compared, the highest chitin deacetylase producing strain was identified as Rhizopus oligosporus NS1. The highest enzyme activity was determined after being cultured for 4 days from 10x10x10x10x10x10 inoculum of two days old spores/ml, in 50 ml of the medium that contained 1.5% glucose, 2.5% bactopeptone and 0.4% yeast extract, initial pH 5.0. The optimal cultivation conditions for chitin deacetylase production were shaking at 150 rpm, 30+-2 ํC, for 4 days, 0.948 mU/ml of chitin deacetylase activity was obtained. The results of the extraction and purification of chitin deacetylase from R.oligosporus NS1 showed the fractional precipitation with 55-85% saturation of ammonimu sulafate and followed by columm chromatography on DEAE-cellulose and Sephadex G-75 gel filtration found 24.4 fold increase in the purity and 6.7% of recorvey from the crude enzyme. The molecular weight of the purified enzyme. estimated via gel filtration, was 29,000 daltons. Analysis of the purified enzyme on SDS-PAGE revealed a single prominent band with molecular weight of 28,000 daltons. The resule suggested that the enzyme chitin deacetylase consisted of a single polypeptide. The optimal temperature and pH of purified enzyme were determined. To be at 55 ํC and pH 6.5 in acetate buffer. The enzyme was found to be stable in the pH range of 4.5-9.0 and temperature 20-50 ํC. Chitin powder and chitosan powder with 75.9-93.8% degree of deacetylation were incubated with purified enzyme. The hydrolyzed activities were quite low after 6 hours of incubation period. It might indicate that the hydrolysis activities of this enzyme is better when chitin-chitosan were in a aqueous suspension than in the powder form.
