Protein Research Department, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications, Alexandria, Egypt.
Biomed Res Int. 2013;2013:175012. doi: 10.1155/2013/175012. Epub 2013 Jul 11.
Novel keratin-degrading bacteria were isolated from sand soil samples collected from Minia Governorate, Egypt. In this study, the isolates were identified as Bacillus amyloliquefaciens MA20 and Bacillus subtilis MA21 based on morphological and biochemical characteristics as well as 16S rRNA gene sequencing. B. amyloliquefaciens MA20 and B. subtilis MA21 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 by B. amyloliquefaciens MA20 and B. subtilis MA21 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.
从埃及米尼亚省采集的沙土样本中分离到新型角蛋白降解细菌。本研究根据形态学和生化特征以及 16S rRNA 基因测序，将分离株鉴定为解淀粉芽孢杆菌 MA20 和枯草芽孢杆菌 MA21。当在含有 1%羊毛直纺作为唯一碳氮源的矿物培养基中培养时，解淀粉芽孢杆菌 MA20 和枯草芽孢杆菌 MA21 产生碱性角蛋白酶丝氨酸蛋白酶。这两种菌株在 pH7 和 37°C 下，5 天内即可将羊毛完全降解为粉末。在这些条件下，解淀粉芽孢杆菌 MA20 和枯草芽孢杆菌 MA21 产生的蛋白酶的最大活性分别为 922 和 814 U/ml。蛋白酶的最适温度和 pH 值分别为 60°C 和 9。然而，角蛋白酶在针对酪蛋白 Hammerstein 时，在广泛的温度和 pH 值范围内稳定。此外，蛋白酶抑制剂研究表明，由于对 PMSF 的敏感性，所产生的蛋白酶属于丝氨酸蛋白酶，而在存在 EDTA 时，它们部分受到抑制。这两种蛋白酶在大多数有机溶剂中稳定，并被金属增强，这表明它们在生物技术应用（如羊毛工业）中有潜在的用途。
