AUTHOR=Bokveld Amahle , Nnolim Nonso E. , Nwodo Uchechukwu U. 

TITLE=Chryseobacterium aquifrigidense FANN1 Produced Detergent-Stable Metallokeratinase and Amino Acids Through the Abasement of Chicken Feathers

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.720176

DOI=10.3389/fbioe.2021.720176

ISSN=2296-4185

ABSTRACT=Microbial keratinases’s versatility in the benefication of keratinous waste biomass into high value products prompts its application in diverse sphere hence, advancing green technology and the bioeconomy. Consequently, a feather-degrading Chryseobacterium aquifrigidense FANN1 was used to produce keratinase, and its biochemical properties determined. The fermentation process conditions were optimized, and the liberated amino acids in the cell-free hydrolysates profiled. FANN1 showed a maximum keratinase yield of 1664.55 ± 42.43 U/mL after 72 h, at optimal process conditions that included initial medium pH of 8, incubation temperature of 30oC, 4% inoculum size (v/v), and 15 (g/L) of chicken feathers. 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 (40–50oC). EDTA and 1,10-phenanthroline inhibited the keratinase activity, and that suggests a metallo-keratinase. FANN1 keratinase 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, H2O2, 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 Fe3+ (120 ± 5.06%), Ca2+ (100 ± 10.33%), Na+ (122 ± 2.95%), Al3+ (106 ± 10.33%); while Co2+ (68 ± 8.22%) and Fe2+ (51 ± 8.43%) elicited the most repressive effect on keratinase activity. The findings suggest that C. aquifrigidense FANN1 is a potential candidate for keratinous wastes bio-recycling, and the associated keratinase has a good prospect for application in detergent formulation.