Wool, hooves, horns, hair, nails, and feathers all include keratins as structural constituents. Each year, 40 million tonnes of keratinous wastes are produced in the United States, Brazil, and China (Sharma and Gupta 2016; Alwakeel et al. 2021). The meat industry produces millions of tonnes of keratinous wastes at slaughterhouses across the world per year (Verma et al. 2017). Up to two million tonnes of chicken feathers are produced worldwide (Reddy et al. 2021). Keratins are insoluble fibrillar proteins found on vertebrates' outer protective surfaces. Because of the solid stabilization of their polypeptide chains and the many disulfide connections that bridge these chains, keratinous materials are noted for their exceptional stability (Hassan et al. 2020a). Current keratin waste treatment methods include landfilling, chemical treatment, and incineration (Khumalo et al. 2020). These treatments are inadequate but since they 1) reduce soil space; 2) increase the amount of toxic chemicals such as halogens and salts in water bodies, endangering aquatic life; 3) increase greenhouse gas emissions, contributing to global warming; and 4) increase eutrophication due to the high amount of nitrogen and alkalinity in aquatic physiology (Vidmar and Vodovnik 2018).
Common protein-degrading enzymes, such as pepsin and papain, do not digest keratins. Keratinous wastes management requires a low-cost solution, particularly in underdeveloped nations. Fungi and bacteria are known to hydrolyze keratinous materials by producing extracellular keratinolytic enzymes (Gafar et al. 2020; Bohacz et al. 2020; Nnolim et al. 2020). Different fungi, such as Aspergillus, Chrysosporium, Trichophyton, and Microsporum, release keratinases that are generally extracellular inducible enzymes (Fang et al. 2013; Akhter et al. 2020; Akram et al. 2020). Keratinase powder, for example, is a commercial product made from the bacteria Bacillus licheniformis and the fungus Parengyodontium album. In the pharmaceutical industry, keratinases are utilized in the manufacturing of vaccines and the creation of bioactive peptides and serums, as well as treatment of calluses, keratinized skin, psoriasis, and acne (Avdiyuk and Varbanets 2019). Keratinases are used in the production of cosmetics such as anti-dandruff shampoos, nutritious lotions, and creams, as well as in feed formulae, nitrogen fertilizers, and leather industry (Gafar et al. 2020; Abdel-Fattah et al. 2018; Moridshahi et al. 2020). Another unique application is the utilization of keratinases to remediate wastewater including keratin wastes (Vidmar and Vodovnik 2018).
Collagenases enzymes have the ability to hydrolyze peptide bonds in both native and denatured collagen. They are widely employed not only in the chemical and medical sectors, but also in food and fundamental biological science (Hisano et al. 1989). Collagen may be created in excess of the desired quantity, in inappropriate locations, or may not disintegrate after a given period of time. In such circumstances, injectable collagenase or collagenase ointment can aid in collagen decomposition. Collagenase-producing microorganisms and their collagenases play critical roles in collagen degradation and organic nitrogen recycling in the ocean. However, only a few collagenase-producing bacteria have been so far discovered over the last 40 years, including Pseudomonas marinoglutinosa (Hanada et al. 1973), Clostridium histolyticum (Van Wart and Steinbrink 1981), Pseudomonas sp. (Hisano et al. 1989), Bacillus licheniformis N22 (Asdornnithee et al. 1994), Bacillus subtilis FS-2 and Bacillus subtilis M2-4 (Tran and Nagano 2002), Flocculibacter collagenilyticus (Li et al. 2021), as well as from Candida albicans URM3622 (Lima et al. 2009).
Several fungal genera such as Acremonium, Aphanoascus, Aspergillus, Chrysosporium, Cladosporium, Doratomyces, Fusarium, Lichtheimia, Microsporum, Paecilomyces, Scopulariopsis, Trichoderma, and Trichophyton have been documented to have the keratinolytic ability. Many of which are human pathogens that have the capacity to destroy both hard and soft keratins (Köhler et al. 2015). On the other hand, the non-pathogenic fungi, on the other hand, have industrial use since they do not cause disease. As a result, more research into suitable microbes is needed to develop safe keratinase producers. However, because the majority of these microorganisms lacked keratinase and collagenase activity, their applications were limited. Thus, the purpose of this work was to find suitable and efficient fungal species capable of decomposing native chicken feather to create keratinase and, for the first time, collagenase for use in diverse biotechnological applications.