College of Food Science and Technology of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology Research Center of Seafood, Guangdong Province Engineering Laboratory for Marine Biological Products, Key Laboratory of Advanced Processing of Aquatic Product of Guangdong Higher Education Institution, Zhanjiang 524088, China.
Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, Jiangxi Agricultural University, Nanchang 330045, China.
Int J Biol Macromol. 2023 Dec 31;253(Pt 5):127194. doi: 10.1016/j.ijbiomac.2023.127194. Epub 2023 Oct 2.
Keratin wastes are abundantly available but rich in hard-degrading fibrous proteins, and the keratinase-producing microorganisms have gained significant attention due to their biodegradation ability against keratinous materials. In order to improve the degradation efficiency of feather keratins, the keratinase gene (kerJY-23) from our previously isolated feather-degrading Ectobacillus sp. JY-23 was overexpressed in Bacillus subtilis WB600 strain. The recombinant KerJY-23 strain degraded chicken feathers rapidly within 48 h, during which the activities of disulfide reductase and keratinase KerJY-23 were sharply increased, and the free amino acids especially the essential phenylalanine and tyrosine were significantly accumulated in feather hydrolysate. The results of structural characterizations including scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction, and X-ray photoelectron spectroscopy, demonstrated that the feather microstructure together with the polypeptide bonds and SS bonds in feather keratins were attacked and destroyed by the recombinant KerJY-23 strain. Therefore, the recombinant KerJY-23 strain contributed to feather degradation through the synergistic action of the secreted disulfide reductase to break the SS bonds and keratinase (KerJY-23) to hydrolyze the polypeptide bonds in keratins. This study offers a new insight into the underlying mechanism of keratin degradation, and provides a potential recombinant strain for the valorization of keratin wastes.
角蛋白废物大量存在，但富含难以降解的纤维状蛋白质，由于其对角蛋白物质的生物降解能力，产角蛋白酶的微生物引起了人们的极大关注。为了提高羽毛角蛋白的降解效率，我们先前从羽毛降解埃希氏菌 JY-23 中分离到的角蛋白酶基因（kerJY-23）在枯草芽孢杆菌 WB600 菌株中得到了过表达。重组 KerJY-23 菌株在 48 小时内迅速降解鸡毛，在此期间，二硫键还原酶和角蛋白酶 KerJY-23 的活性急剧增加，羽毛水解物中游离氨基酸特别是必需的苯丙氨酸和酪氨酸明显积累。结构特征分析的结果，包括扫描电子显微镜、傅里叶变换红外光谱、X 射线衍射和 X 射线光电子能谱，表明鸡毛的微观结构以及角蛋白中的多肽键和 SS 键都受到了重组 KerJY-23 菌株的攻击和破坏。因此，重组 KerJY-23 菌株通过分泌的二硫键还原酶打破 SS 键和角蛋白酶（KerJY-23）水解角蛋白中的多肽键的协同作用促进了羽毛的降解。本研究为角蛋白降解的潜在机制提供了新的见解，并为角蛋白废物的增值提供了一种有潜力的重组菌株。
