The bioaccumulation of keratinous wastes from poultry and dairy industries poses a danger of instability to the biosphere due to resistance to common proteolysis and as such, microbial- and enzyme-mediated biodegradation are discussed. In submerged fermentation medium, Proteus vulgaris EMB-14 utilized and efficiently degraded feather, fur and scales by secreting exogenous keratinase. The keratinase was purified 14-fold as a monomeric 49 kDa by DEAE-Sephadex A-50 anion exchange and Sephadex G-100 size-exclusion chromatography. It exhibited optimum activity at pH 9.0 and 60 °C and was alkaline thermostable (pH 7.0–11.0), retaining 87% of initial activity after 1 h pre-incubation at 60 °C. The Km and Vmax of the keratinase with keratin azure were respectively 0.283 mg/mL and 0.241 U/mL/min. Activity of P. vulgaris keratinase was stimulated by Ca2+, Mg2+, Zn2+, Na+ and maintained in the presence of some denaturing agents, except β-mercaptoethanol while Cu2+ and Pb2+ showed competitive and non-competitive inhibition with Ki 6.5 mM and 17.5 mM, respectively. This purified P. vulgaris keratinase could be surveyed for the biotechnological transformation of bioorganic keratinous wastes into valuable products such as soluble peptides, cosmetics and biodegradable thermoplastics.

中文翻译：

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从低成本羽毛粉上生长的普通变形杆菌 EMB-14 纯化的表面活性剂稳定角蛋白酶的生化表征

由于对常见蛋白水解的抵抗力，来自家禽和乳制品行业的角蛋白废物的生物积累对生物圈构成了不稳定的危险，因此，讨论了微生物和酶介导的生物降解。在深层发酵培养基中，Proteus vulgaris EMB-14 通过分泌外源性角蛋白酶利用并有效降解羽毛、毛皮和鳞片。角蛋白酶通过 DEAE-Sephadex A-50 阴离子交换和 Sephadex G-100 尺寸排阻色谱纯化 14 倍，作为单体 49 kDa。它在 pH 9.0 和 60 °C 下表现出最佳活性，并且对碱性热稳定（pH 7.0-11.0），在 60 °C 下预孵育 1 小时后仍保留初始活性的 87%。角蛋白天蓝色角蛋白酶的 Km 和 Vmax 分别为 0.283 mg/mL 和 0.241 U/mL/min。P. vulgaris 角蛋白酶的活性受 Ca2+ 刺激，Mg2+、Zn2+、Na+ 和在一些变性剂存在下保持不变，β-巯基乙醇除外，而 Cu2+ 和 Pb2+ 分别与 Ki 6.5 mM 和 17.5 mM 表现出竞争性和非竞争性抑制。这种纯化的 P. vulgaris 角蛋白酶可用于将生物有机角蛋白废物的生物技术转化为有价值的产品，如可溶性肽、化妆品和可生物降解的热塑性塑料。