PRODUCTION OF AMYLASE FROM INDIGENOUSLY ISOLATED STRAIN OF Aureobasidium pullulans AND ITS HYPER PRODUCING MUTANT

Abstract

New isolate obtained from leaf surfaces of Spinacia olevacea, Brassica oleracea and Coriandrum sativum was identified as Aureobasidium pullulans on the basis of cultural, morphological, biochemical and molecular characterization. The factors such as inoculums size, incubation time, sources of starch, and concentration of starch, sources of carbon and nitrogen, effect of initial pH and effect of temperature affecting production of amylase were optimized in present study. The optimum pH, temperature and incubation period for enzyme production were 5, 25OC and 5 days respectively. Among different sources of starch tested potato starch was shown to be the best. Potato starch at 1% was recorded to be the best concentration of starch for enzyme production. Sodium nitrate was ideal nitrogen source. At optimum conditions Aureobasidium pullulans Cau 19 has shown amylase activity 800U/L, which is twofold higher than before optimization. For the improvement of Aureobasidium pullulans Cau 19, the parental strain, after optimization of the cultural conditions, was subjected to UV irradiation for 8 min. Total 286 mutants were checked, out of which 9 mutant strains showing comparatively greater hydrolysis zone were selected for further study. Aureobasidium pullulans UVm 276 mutant has shown amylase activity which is 2.78 fold that of the wild type strain. Thus these findings have more impact on enzyme economy for biotechnological applications of microbial amylases.