Purification and characterisation of an acidic and antifungal chitinase produced by a Streptomyces sp.

Abstract

An extremely acidic extracellular chitinase produced by a Streptomyces sp. was purified 12.44-fold by ammonium sulphate precipitation, ion-exchange chromatography and gel-permeation chromatography and further characterised. The molecular mass of the enzyme was estimated to be about 40kDa by SDS–PAGE. The optimum pH and temperature of the purified enzyme were pH 2 and 6, and 50°C respectively. The enzyme showed high stability in the acidic pH range of 2–6 and temperature stability of up to 50°C. Additionally, the effect of some cations and other chemical compounds on the chitinase activity was studied. The activity of the enzyme was considerably retained under salinity conditions of up to 3%. The Km and Vmax values of the enzyme were determined to be 6.74mgmL−1 and 61.3Umg−1 respectively using colloidal chitin. This enzyme exhibited antifungal activity against phytopathogens revealing a potential biocontrol application in agriculture.