Purification, Characterization and Antifungal Activity of Chitinase from Serratia marcescens Isolated from Fresh Vegetables

Seven [35%] and five [25%] Serratia marcescens isolates were obtained out of 20 samples of lettuce and 20 samples of spinach, resp ectively, taken from different locations in a farm in Baghdad city. The isolate that produced chitinase in higher level was chosen to purify chitinase through several stages of purification including: ammonium sulfate precipitation, DEAEsep hadex ion exchange chrom atograpgy and sephadex G-200 gel filtration with 89.5- fold purification and 30% recovery. The purified chitinase was characterized and the molecular weight of enzyme was 59000 daltons by using gel filtration chromatography . The optimum pH and temperature of the purified chitinase were 6.0 and 50° c, respectively, and the purified enzyme was stable on pH 5-7 up to 50° c. The enzyme was activated by Ca^+2 , Cu^+2 , M g^+2 and inhibited by Hg^+2. In addition , Triton x-100 and n-ethy lmaleimide increased the chitinase activity while EDT A, methanol, ethanol and acetone inhibited enzyme activity; and this indicates that chitinase is a metaloenzyme. Chitinase showed stronger inhibitory activity to Fusarium solaini compared with Aspergillus flavus with p ercent of inhibition 83 and 69%, resp ectively . Therefore, this research leads to increase interest by using the chitinase as biocontrol agent of phytopathogenic fun gi and insects , p roduction of chito –oligosaccharides,p reparartion of sphaeroplast and p rotoplast from yeast and fungi and bioconversion of chitin waste to single cell protein for animal feed.