Production and Characterization of Keratinolytic Protease from New Wool-DegradingBacillusSpecies Isolated from Egyptian Ecosystem

摘要

Novel keratin-degrading bacteria were isolated from sand soil samples collected from Minia Governorate, Egypt. In this study, the isolates were identified asBacillus amyloliquefaciensMA20 andBacillus subtilisMA21 based on morphological and biochemical characteristics as well as 16S rRNA gene sequencing.B. amyloliquefaciensMA20 andB. subtilisMA21 produced alkaline keratinolytic serine protease when cultivated in mineral medium containing 1% of wool straight off sheep as sole carbon and nitrogen source. The two strains were observed to degrade wool completely to powder at pH 7 and 37°C within 5 days. Under these conditions the maximum activity of proteases produced byB. amyloliquefaciensMA20 andB. subtilisMA21 was 922 and 814 U/ml, respectively. The proteases exhibited optimum temperature and pH at 60°C and 9, respectively. However, the keratinolytic proteases were stable in broad range of temperature and pH values towards casein Hammerstein. Furthermore the protease inhibitor studies indicated that the produced proteases belong to serine protease because of their sensitivity to PMSF while they were inhibited partially in presence of EDTA. The two proteases are stable in most of the used organic solvents and enhanced by metals suggesting their potential use in biotechnological applications such as wool industry.