Keratinase Biosynthesis from Waste Poultry Feathers for Proteinaceous Stain Removal

Abstract

This study is aimed at assessing the keratinase production related to industrial detergent applications from a newly isolated Bacillus cereus IIPK35. The production was optimized through submerged fermentation by a one-variable-at-a-time method, followed by the response surface methodology, using waste chicken feathers as a carbon source and resulted in a 5-fold increase in keratinase production in 48 h (103.79 U/mL) when supplemented with 1.43% w/v feather and other nutrients. Time-course study of 120 h revealed a direct relationship among microbial growth, feather degradation, sulfite generation, production of keratinase, oligopeptide, and total protein. The sulfite generation in the culture filtrate suggested the possible sulfur mineralization by disulfide reductase produced by IIPK35. At optimized conditions, cell free fermented broth was enriched with 12 amino acids copiously: threonine (8.52 μg/mL), serine (7.55 μg/mL), and phenylalanine (7.13 μg/mL). Fourier transform infrared analysis reflected the cleavage of peptide bonds associated with feather keratin degradation. IIPK35 keratinase exhibited 79−88% stability and compatibility with commercial detergents and thus appeared to be a promising approach toward laundry detergents. The washing simulation experiment with low supplementation of keratinase combined with detergent demonstrated good destaining of proteinaceous stains without damaging the fabric structure and strength. Thus, the crude keratinase from B. cereus IIPK35 could be considered as a potential bioadditive in detergent formulation.

Production of surfactant-stable keratinase from Bacillus cereus YQ15 and its application as detergent additive

“…The optimal inoculum size differed from that of B. subtilis KD-N2 (10%) [ 29 ]. And our finding is similar to B. cereus IIPK35, whose inoculum size was 2% for high keratinase production [ 23 ]. Fermenting temperature usually influences the metabolism of microorganisms and exhibits a significant impact on the biosynthesis of target enzymes.…”

“…Fermenting temperature usually influences the metabolism of microorganisms and exhibits a significant impact on the biosynthesis of target enzymes. In this study, the optimum growth temperature for keratinase production is 35 °C, which is similar to some other bacterial keratinases with an optimum temperature range of 30 to 40 °C [ 23 , 30 , 31 ]. The results indicated that B. cereus YQ15 belongs to mesophilic bacteria, exhibiting superior potential in industrial application than the thermophiles because of the less energy cost from this perspective.…”

“…It is similar to the enzymes from B. cereus IIPK36 and Bacillus sp. WF146 [ 23 , 24 ]. We speculated that the reason for it might be that those enzymes lack disulfide bond-reducing potential, which cleaves the disulfide bond to accelerate decomposing of feather’s recalcitrant structure [ 4 ].…”

“…Comparing the control, the residual activities retained more than 70% at 7 mg/mL and more than 60% at the 10 mg/mL in the presence of the tested commercial detergents. It is generally known that the high stability of enzymes with detergents indicated its suitability for use as a detergent additive [ 23 , 45 ]. Correspondingly, there have been various reports on the compatibility of microbial keratinases with commercial detergents which validated the suitable potential of alkaline keratinases as a detergent additive [ 33 ].…”

Parametrically optimized feather degradation by Bacillus velezensis NCIM 5802 and delineation of keratin hydrolysis by multi-scale analysis for poultry waste management

“…The experimental data were fitted to a second-order polynomial equation through multiple regression analysis, and analysis of variance (ANOVA) indicated the competence of the model so obtained. Mutual interactions between the independent variables were characterized by three-dimensional response surface plots 29 .…”