Keratinases produced by Chryseobacterium proteolyticum FGNn and Pseudomonas aeruginosa GNFx liberated amino acids from poultry feathers

Abstract

AbstractThe agro-industrial sector generates diverse waste that requires effective handling to mitigate economic loss and pollution. Consequently, this study assessed bacterial isolates from poultry dumpsites for feather decomposition and keratinase production capacity. The protein hydrolysates generated from feather dismemberment by two bacteria identified as Chryseobacterium proteolyticum FGNn (accession no. MW165478) and Pseudomonas aeruginosa GNFx (accession no. MW165479) were profiled for amino acids composition. The biochemical properties of the bacteria-associated keratinases were determined. Initial keratinase production (with percentage feather degradation), demonstrated by the isolates, was 693.63 ± 62.99 U/mL (81%) and 619.09 ± 37.28 (76%) against FGNn and GNFx, respectively. At optimized process conditions, C. proteolyticum and P. aeruginosa extracellular keratinase production was 1756.36 ± 2.57 U/mL at 72 h and 2055.45 ± 50.14 U/mL at 96 h, respectively. Analysis of the feather hydrolysates showed a relatively high abundance of arginine (3.18%) and glycine (3.26%) for FGNn and glutamic acid (6.05%), serine (3.31%), aspartic acid (4.74%), glycine (3.71%), alanine (3.43%), valine (3.09%), and leucine (3.23%) for GNFx. The keratinolytic proteases showed pH and temperature optima of 8.0 and 50°C against FGNn, and 8.0 and 60°C against GNFx. GNFx keratinase was thermostable, displaying a half-life time of more than 60 min at 80°C. In addition, GNFx keratinolytic enzyme was chemical agent tolerant post-treatment. The findings underlined the significance of C. proteolyticum FGNn and P. aeruginosa GNFx as suitable in the valorisation of keratinous biomass. Also, the robust stability profile of GNFx keratinase highlights its prospects in green technology.