以羽毛粉为唯一碳氮源，从家禽厂土壤中筛选获得一株角蛋白酶产生菌，复筛角蛋白酶活力达46.89 U(mL-1。经形态特征和16S rRNA鉴定，该菌株被命名为Bacillus subtilis KS12。研究pH、温度、离子、表面活性剂、氧化剂和有机溶剂对B. subtilis KS12产角蛋白酶活性的影响。结果表明：该菌株产角蛋白酶最适反应pH 7.5，最适温度37℃，在pH 8.0～9.0范围内稳定性高，处理 1 h相对酶活力仍达95.7%～97.2%，60℃和80℃保温1 h相对酶活力分别为61.4%和59.5%；5 mmol(L-1 Ca2+和Mg2+对酶活性有促进作用，其中Mg2+尤为明显，相对酶活力达159%，Cu2+(5 mmol(L-1)抑制角蛋白酶活性，相对酶活力仅有3.7%；5%的吐温80可以提高角蛋白酶活性，相对酶活力为140.4%；有机溶剂异丙醇、甲醛、甲醇、乙醇、异戊醇和二甲苯抑制角蛋白酶活性。
A strain with high keratinase activity of 46.89 U(mL-1 was isolated from poultry plant soil samples by using feather powder as the sole carbon source and nitrogen source. The strain was identified as Bacillus subtilis KS12 by the morphological characterize, and 16S rRNA sequence analysis. The effects of pH, temperature, ions, surfactants, oxidants and organic solvents on the keratinase activity of B. subtilis KS12 were investigated. The result showed that the optimum pH and temperature of the keratinase of the strain were 7.5 and 37℃, respectively. The keratinase was stabile between pH 8.0 and 9.0 with the relative enzyme activity of 95.5%~97.2% for 1 h, and the relative enzyme activity were 61.4% and 59.5%, respectively, at 60 ℃ and 80 ℃ for 1 h. The keratinase activity was improved by 5 mmol(L-1 Ca2+ and Mg2+, especially Mg2+ with the relative enzyme activity of 159%, and inhibited by Cu2+ (5 mmol(L-1) with the relative enzyme activity of 3.7%, and 5% of Tween 80 expressed a positive effectt on the keratinase activity with 140.4%. Furthermore, the keratinase activity of B. subtilis KS12 were inhibited by isopropanol, formaldehyde, methanol, ethanol, isoamyl alcohol and xylene.