Purification and Characterization of Chitinase Produced by Endophytic Streptomyceshygroscopicus Against Some Phytopathogens

摘要

Microorganisms, which secret a complex of mycolytic enzymes are considered to be possible biological control agents of plant diseases. Since Chitinases are digestive enzymes that break down glycosidic bonds in chitin. In this present study, an industrial enzyme chitinase produced by endophyticStreptomyceswas purified and its antifungal activity was investigated against phytopathogens i.e. Rhizoctoniasolani,Fusariumoxysporum, Alternaria alternate, Aspergillusniger, Aspergillusflavus, Sclerotiniascleotiorum, Phytophthoraparasiticaand Botrytis cinerea.A chitinasewas produced byendophyticStreptomyceshygroscopicus in cultures containing chitin as the sole substrate that degrade chitin in 0.9 mm zone of clearance. The purification steps included ammonium sulfate precipitation, with columns of DEAE-Sepharose anion exchange chromatography and Sephacryl S-400 high resolution gel chromatography. The method gave a 5.4 fold increase of the specific activity and had a yield of 18%. The molecular weight of the chitinase was found to be around 80.8, 78 and 76 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) technique. Chitinase was optimally active at pH of 6.0 to7.0 and at 30℃. The chitanase were found to inhibit the growth of all phytopathogenic fungi.