Bokveld Amahle, Nnolim Nonso E, Nwodo Uchechukwu U
SAMRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, South Africa.
Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa.
Front Bioeng Biotechnol. 2021 Aug 6;9:720176. doi: 10.3389/fbioe.2021.720176. eCollection 2021.
Microbial keratinases' versatility in the beneficiation of keratinous waste biomass into high-value products prompts their application in diverse spheres hence, advancing green technology and the bioeconomy. Consequently, a feather-degrading FANN1 (NCBI: MW169027) was used to produce keratinase, and its biochemical properties were determined. The optimization of physicochemical parameters and analysis of the free amino acid constituents of the feather hydrolysate were also carried out. FANN1 showed a maximum keratinase yield of 1,664.55 ± 42.43 U/mL after 72 h, at optimal process conditions that included initial medium pH, incubation temperature, inoculum size, and chicken feather concentration of 8, 30°C, 4% (v/v), and 15 (g/L), respectively. Analysis of degradation product showed 50.32% and 23.25% as the protein value and total free amino acids, respectively, with a relatively high abundance of arginine (2.25%) and serine (2.03%). FANN1 keratinase was optimally active at pH 8.0 and relatively moderate to high temperature (40-50°C). EDTA and 1,10-phenanthroline inhibited the keratinase activity, and that suggests a metallo-keratinase. The enzyme showed remarkable stability in the presence of chemical agents, with residual activity 141 ± 10.38%, 98 ± 0.43%, 111 ± 1.73%, 124 ± 0.87%, 104 ± 3.89%, 107 ± 7.79%, and 112 ± 0.86% against DTT, HO, DMSO, acetonitrile, triton X-100, tween-80, and SDS, respectively. The residual activity of FANN1 keratinase was enhanced by Sunlight (129%), Ariel (116%), MAQ (151%), and Surf (143%) compared to the control after 60 min preincubation. Likewise, the enzyme was remarkably stable in the presence Fe (120 ± 5.06%), Ca (100 ± 10.33%), Na (122 ± 2.95%), Al (106 ± 10.33%); while Co (68 ± 8.22%) and Fe (51 ± 8.43%) elicited the most repressive effect on keratinase activity. The findings suggest that FANN1 is a potential candidate for keratinous wastes bio-recycling, and the associated keratinase has a good prospect for application in detergent formulation.
微生物角蛋白酶在将含角蛋白的废弃生物质转化为高价值产品方面具有多功能性，这促使它们在不同领域得到应用，从而推动了绿色技术和生物经济的发展。因此，使用一株羽毛降解菌FANN1（NCBI：MW169027）来生产角蛋白酶，并测定其生化特性。还进行了理化参数的优化以及羽毛水解产物游离氨基酸成分的分析。在最佳工艺条件下，即初始培养基pH值为8、培养温度为30°C、接种量为4%（v/v）、鸡毛浓度为15（g/L）时，FANN1在72小时后显示出最大角蛋白酶产量为1,664.55±42.43 U/mL。降解产物分析表明，蛋白质值和总游离氨基酸分别为50.32%和23.25%，精氨酸（2.25%）和丝氨酸（2.03%）的含量相对较高。FANN1角蛋白酶在pH 8.0以及相对适中至高的温度（40 - 50°C）下具有最佳活性。EDTA和1,10 - 菲咯啉抑制角蛋白酶活性，这表明它是一种金属角蛋白酶。该酶在化学试剂存在下表现出显著的稳定性，对二硫苏糖醇（DTT）、过氧化氢（HO）、二甲基亚砜（DMSO）、乙腈、曲拉通X - 100、吐温 - 80和十二烷基硫酸钠（SDS）的残留活性分别为141±10.38%、98±0.43%、111±1.73%、124±0.87%、104±3.89%、107±7.79%和112±0.86%。与对照相比，在预孵育60分钟后，阳光（129%）、碧浪（116%）、立白（151%）和汰渍（143%）增强了FANN1角蛋白酶的残留活性。同样，该酶在铁（120±5.06%）、钙（100±10.33%）、钠（122±2.95%）、铝（106±10.33%）存在下显著稳定；而钴（68±8.22%）和铁（51±8.43%）对角蛋白酶活性产生最显著的抑制作用。研究结果表明，FANN1是含角蛋白废物生物回收的潜在候选菌株，其相关角蛋白酶在洗涤剂配方中有良好的应用前景。
