Purification and Characterization of Chitinase Produced by Endophytic St re ptomyceshygroscopicus Against Some Phytopathogens

Abstract

Microorganisms, wh ich secret a co mplex o f mycolytic enzy mes are considered to be possible bio logical control agents of plant d iseases. Since Ch itinases are digestive enzy mes that break down glycosidic bonds in chit in. In this present study, an industrial en zy me chitinase produced by endophyticStreptomyceswas purified and its antifungal act ivity 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 ammoniu m sulfate precip itation, with colu mns of DEA E-Sepharose anion exchange chromatography and Sephacryl S-400 high resolution gel chro matography. The method gave a 5.4 fold increase of the specific activ ity and had a y ield of 18%. The mo lecular weight of the chit inase was found to be around 80.8, 78 and 76 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PA GE) technique. Chit inase was optimally active at pH of 6.0 to7.0 and at 30℃. The ch itanase were found to inhibit the growth of all phytopathogenic fungi.