Microbial Keratinase: Next Generation Green Catalyst and Prospective Applications

Abstract

The search for novel renewable products over synthetics hallmarked this decade and those of the recent past. Most economies that are prospecting on biodiversity for improved bio-economy favor renewable resources over synthetics for the potential opportunity they hold. However, this field is still nascent as the bulk of the available resources are non-renewable based. Microbial metabolites, emphasis on secondary metabolites, are viable alternatives; nonetheless, vast microbial resources remain under-exploited; thus, the need for a continuum in the search for new products or bio-modifying existing products for novel functions through an efficient approach. Environmental distress syndrome has been identified as a factor that influences the emergence of genetic diversity in prokaryotes. Still, the process of how the change comes about is poorly understood. The emergence of new traits may present a high prospect for the industrially viable organism. Microbial enzymes have prominence in the bio-economic space, and proteases account for about sixty percent of all enzyme market. Microbial keratinases are versatile proteases which are continuously gaining momentum in biotechnology owing to their effective bio-conversion of recalcitrant keratin-rich wastes and sustainable implementation of cleaner production. Keratinase-assisted biodegradation of keratinous materials has revitalized the prospects for the utilization of cost-effective agro-industrial wastes, as readily available substrates, for the production of high-value products including amino acids and bioactive peptides. This review presented an overview of keratin structural complexity, the potential mechanism of keratin biodegradation, and the environmental impact of keratinous wastes. Equally, it discussed microbial keratinase; vis-à-vis sources, production, and functional properties with considerable emphasis on the ecological implication of microbial producers and catalytic tendency improvement strategies. Keratinase applications and prospective high-end use, including animal hide processing, detergent formulation, cosmetics, livestock feed, and organic fertilizer production, were also articulated.

Novel recombinant keratin degrading subtilisin like serine alkaline protease from Bacillus cereus isolated from marine hydrothermal vent crabs

“…A drawback of this process is that large sulfide amounts are produced which are toxic, having a high biological oxygen demand (BOD) and chemical oxygen demand (COD), and producing a high amount of total suspended solids (TSS) 14 . To overcome the risk associated with the degradation of keratin substrates, the microbial keratinases are studied extensively in bio-cycling of agro-industrial wastes in cost-effective and eco-friendly ways 15 . Keratinase based formulations like Valkerase, Versazyme, CIBENZA, DP100 and FEED-0001 are useful for the improvement of the nutritional values of animal feeds 16 .…”

Chicken Feathers Waste Management by Microbial as a Sustainable and Tool Environmental Friendly

“…However, the mechanisms behind this degradation still require further studies. As reported by Nnolim et al [25], keratinolysis can be catalyzed by a single keratinase, or more efficiently, in synergy with other enzymes such as disulfide reductases to breakdown the disulfide bond, peptidases and trypsin [26].…”

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

“…However, the thermo-chemical-mechanical approach for valorizing chicken feathers into feedstock supplements compromises nutrients' integrity and involves high energy input (Abdel-Fattah et al, 2018). The keratinous agro-residues valorization approach involving the application of keratinolytic microbes is considered sustainable and environmentally friendly (Nnolim et al, 2020a). Amino acid-rich protein hydrolysates from the microbial dismemberment of keratinous residues serve as cheap protein supplements to formulate livestock feeds (Adetunji and Adejumo, 2018).…”

“…Keratinolytic protease has been used in feeds to improve the nutrients' bioaccessibility and bioassimilability (Wang et al, 2006;Adetunji and Adejumo, 2018). The versatility of microbial keratinase accounts for the array of applications of the enzyme in advancing green technological processes in the bioeconomy (Nnolim et al, 2020a).…”