Nnolim Nonso E, Mpaka Lindelwa, Okoh Anthony I, Nwodo Uchechukwu U
SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice 5700, South Africa.
Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.
Microorganisms. 2020 Aug 27;8(9):1304. doi: 10.3390/microorganisms8091304.
Keratinases are considerably gaining momentum in green technology because of their endowed robustness and multifaceted application potentials, such as keratinous agro-wastes valorization. Therefore, the production of novel keratinases from relatively nonpathogenic bacteria grown in agro-wastes formulated medium is cost-effective, and also imperative for the sustainability of thriving bioeconomy. In this study, we optimized keratinase production by sp. Nnolim-K1 grown in chicken feather formulated medium. The produced keratinase (KerBNK1) was biochemically characterized and also, the keratinase-encoding gene () was amplified and sequenced. The optimal physicochemical conditions for extracellular keratinase production determined were 0.8% () xylose, 1.0% () feather, and 3.0% () inoculum size, pH 5.0, temperature (25 °C) and agitation speed (150 rpm). The maximum keratinase activity of 1943.43 ± 0.0 U/mL was achieved after 120 h of fermentation. KerBNK1 was optimally active at pH and temperature of 8.0 and 60 °C, respectively; with remarkable pH and thermal stability. KerBNK1 activity was inhibited by ethylenediamine tetra-acetic acid and 1,10-phenanthroline, suggesting a metallo-keratinase. The amplified showed a band size of 1104 bp and the nucleotide sequence was submitted to the GenBank with accession number MT268133. sp. Nnolim-K1 and the keratinase displayed potentials that demand industrial and biotechnological exploitations.
由于角蛋白酶具有强大的稳定性和多方面的应用潜力，如角质化农业废弃物的增值利用，因此在绿色技术领域正越来越受到关注。因此，利用在农业废弃物配制培养基中生长的相对非致病性细菌生产新型角蛋白酶既具有成本效益，对于蓬勃发展的生物经济的可持续性也至关重要。在本研究中，我们优化了在鸡毛配制培养基中生长的Nnolim-K1菌株的角蛋白酶生产。对所产生的角蛋白酶（KerBNK1）进行了生化特性分析，同时对角蛋白酶编码基因进行了扩增和测序。确定的细胞外角蛋白酶生产的最佳理化条件为0.8%（w/v）木糖、1.0%（w/v）羽毛、3.0%（v/v）接种量、pH 5.0、温度（25°C）和搅拌速度（150 rpm）。发酵120小时后，角蛋白酶的最大活性达到1943.43±0.0 U/mL。KerBNK1分别在pH 8.0和温度60°C时具有最佳活性；具有显著的pH和热稳定性。KerBNK1的活性受到乙二胺四乙酸和1,10-菲啰啉的抑制，表明其为金属角蛋白酶。扩增产物显示条带大小为1104 bp，核苷酸序列已提交至GenBank，登录号为MT268133。Nnolim-K1菌株和角蛋白酶显示出需要进行工业和生物技术开发的潜力。
