Keratinolytic activity from new recombinant fusant AYA2000, derived from endophyticMicromonosporastrains

Abstract

Two different endophytic strains, ESRAA1997 and ALAA2000, were isolated from the Egyptian herbal plant Anastatica hierochuntica . The 2 strains produced alkaline serine protease and were identified based on their phenotypic and chemotypic characteristics as different strains of Micromonospora spp. Both strains grew and produced keratinase, using different keratinous waste substances as the sole source of carbon and nitrogen. In our study, the activity and properties of keratinase enzymes of the wild strains ESRAA1997 and ALAA2000 were altered by genetic recombination through protoplast fusion between them, leading to a potent keratinolytic fusant Micromonospora strain AYA2000 with improved properties (activity, stability, specificity, and tolerance to inhibitors). Using a mixture of yeast extract, peptone, and malt extract as a supplement to the bovine hair medium increased keratinase production by 48%, and addition of 1% glucose suppressed enzyme production by Micromonospora strain AYA2000. The enzyme was purified by ammonium sulphate precipitation and DEAE–cellulose chromatography followed by gel filtration. The molecular weight, estimated using SDS–PAGE, was 39 kDa. The enzyme exhibited remarkable activity towards all keratinous wastes used and could also adapt to a broad range of pH and temperatures, with optima at pH 11 and 60 °C. The enzyme was not influenced by chelating reagents, metal ions, or alcohols. These properties make AYA2000 keratinase an ideal candidate for biotechnological application.