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Journal ArticleDOI

Biodegradation of keratin waste: Theory and practical aspects

01 Aug 2011-Waste Management (Pergamon)-Vol. 31, Iss: 8, pp 1689-1701
TL;DR: This study reviews the current knowledge on the ecology and physiology of keratinolytic microorganisms and presents the biodegradation mechanism of native keratin, and methods of keratin waste biotransformation into products of practical industrial and natural value, especially composts, are discussed.
About: This article is published in Waste Management.The article was published on 2011-08-01. It has received 310 citations till now.
Citations
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Journal ArticleDOI
TL;DR: This review discusses the various methods available for the dissolution and extraction of keratin with emphasis on their advantages and limitations, and reports the properties of various keratin-based biomaterials and critically examines how these materials are influenced by the keratin extraction procedure.
Abstract: Keratinous materials such as wool, feathers and hooves are tough unique biological co-products that usually have high sulfur and protein contents A high cystine content (7–13%) differentiates keratins from other structural proteins, such as collagen and elastin Dissolution and extraction of keratin is a difficult process compared to other natural polymers, such as chitosan, starch, collagen, and a large-scale use of keratin depends on employing a relatively fast, cost-effective and time efficient extraction method Keratin has some inherent ability to facilitate cell adhesion, proliferation, and regeneration of the tissue, therefore keratin biomaterials can provide a biocompatible matrix for regrowth and regeneration of the defective tissue Additionally, due to its amino acid constituents, keratin can be tailored and finely tuned to meet the exact requirement of degradation, drug release or incorporation of different hydrophobic or hydrophilic tails This review discusses the various methods available for the dissolution and extraction of keratin with emphasis on their advantages and limitations The impacts of various methods and chemicals used on the structure and the properties of keratin are discussed with the aim of highlighting options available toward commercial keratin production This review also reports the properties of various keratin-based biomaterials and critically examines how these materials are influenced by the keratin extraction procedure, discussing the features that make them effective as biomedical applications, as well as some of the mechanisms of action and physiological roles of keratin Particular attention is given to the practical application of keratin biomaterials, namely addressing the advantages and limitations on the use of keratin films, 3D composite scaffolds and keratin hydrogels for tissue engineering, wound healing, hemostatic and controlled drug release

289 citations

Journal ArticleDOI
TL;DR: This review reports the known functional and bioactive properties of hydrolysates derived from chicken by-products as well their utilisation as source of peptone in microbiological media.

222 citations


Cites background from "Biodegradation of keratin waste: Th..."

  • ...Introduction 1995; Korniłłowicz-Kowalska and Bohacz, 2011)....

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  • ...…show that some Bacillus species of bacteria, actinomycetes and some fungi can effectively degrade keratinous substrates (Fakhfakh et al., 2011; Korniłłowicz-Kowalska and Bohacz, 2011; Williams and Shih, 1989; Lin et al., 1995, 1999; Nagal and Jain, 2010) which they use as sources of C, N, S…...

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  • ...An excellent review by Korniłłowicz-Kowalska and Bohacz (2011) pointed out that the Bacillus licheniformis strains were prominent among the keratinolytic bacteria while among the actinomycetes and fungi, the genus Streptomyces and Chrysosporium respectively, were frequently observed....

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Journal ArticleDOI
TL;DR: A holistic view of the complex molecular self-assembling structure of keratin and knowledge about enzymatic and boosting factors needed for keratin breakdown have been used to formulate a hypothesis for mode of action of the LPMOs in keratin decomposition and for a model for degradation of Keratin in nature.
Abstract: Discovery of keratin-degrading enzymes from fungi and bacteria has primarily focused on finding one protease with efficient keratinase activity. Recently, an investigation was conducted of all keratinases secreted from a fungus known to grow on keratinaceous materials, such as feather, horn, and hooves. The study demonstrated that a minimum of three keratinases is needed to break down keratin, an endo-acting, an exo-acting, and an oligopeptide-acting keratinase. Further, several studies have documented that disruption of sulfur bridges of the keratin structure acts synergistically with the keratinases to loosen the molecular structure, thus giving the enzymes access to their substrate, the protein structure. With such complexity, it is relevant to compare microbial keratin decomposition with the microbial decomposition of well-studied polymers such as cellulose and chitin. Interestingly, it was recently shown that the specialized enzymes, lytic polysaccharide monoxygenases (LPMOs), shown to be important for breaking the recalcitrance of cellulose and chitin, are also found in keratin-degrading fungi. A holistic view of the complex molecular self-assembling structure of keratin and knowledge about enzymatic and boosting factors needed for keratin breakdown have been used to formulate a hypothesis for mode of action of the LPMOs in keratin decomposition and for a model for degradation of keratin in nature. Testing such hypotheses and models still needs to be done. Even now, the hypothesis can serve as an inspiration for designing industrial processes for keratin decomposition for conversion of unexploited waste streams, chicken feather, and pig bristles into bioaccessible animal feed.

178 citations


Cites background or result from "Biodegradation of keratin waste: Th..."

  • ...…focus only on bacterial keratinases (Brandelli 2008; Daroit and Brandelli 2014; Sahni et al. 2015) or include only very limited information about fungal keratinases (Brandelli et al. 2010; Gupta and Ramnani 2006; Gupta et al. 2013; Korniłłowicz-Kowalska and Bohacz 2011; Onifade et al. 1998)....

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  • ...…that there is an overall support to the picture of keratin decomposition given by previous review authors (Brandelli 2008; Brandelli et al. 2010; Daroit and Brandelli 2014; Gupta and Ramnani 2006; Gupta et al. 2013; Korniłłowicz-Kowalska and Bohacz 2011; Onifade et al. 1998; Sahni et al. 2015)....

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Journal ArticleDOI
TL;DR: The structure, properties, history, research, methods of extraction and some recent advancements related to the use of keratin derived biomaterials in the form of a 3-D scaffold, films, fibers, and hydrogels are reviewed.

158 citations


Cites background from "Biodegradation of keratin waste: Th..."

  • ...consist of cystine/cysteine and serine constituted about 20–30% [44]....

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  • ...Kornillowicz-Kowalska observed keratin degradation by using a mixture containing 16 strains of different keratinophilic fungi [44]....

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  • ...Similarly, species of the genus Chrysosporium and Dermatophytes represented as keratinolytic fungi in the literature [44]....

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  • ...About 50% of the sulfur content can be converted to sulfite products mainly depending upon the genus of fungi [44]....

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  • ...Certain bacteria from Bacillus genus and fungi such as keratinophilic fungi, Actinomycetes can completely disintegrate the keratin [44]....

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References
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Journal ArticleDOI
TL;DR: Keratinases stand out among proteases since they attack the keratin residues and hence find application in developing cost-effective feather by-products for feed and fertilizers and their prospective application in the challenging field of prion degradation would revolutionize the protease world in the near future.
Abstract: Microbial keratinases have become biotechnologically important since they target the hydrolysis of highly rigid, strongly cross-linked structural polypeptide “keratin” recalcitrant to the commonly known proteolytic enzymes trypsin, pepsin and papain. These enzymes are largely produced in the presence of keratinous substrates in the form of hair, feather, wool, nail, horn etc. during their degradation. The complex mechanism of keratinolysis involves cooperative action of sulfitolytic and proteolytic systems. Keratinases are robust enzymes with a wide temperature and pH activity range and are largely serine or metallo proteases. Sequence homologies of keratinases indicate their relatedness to subtilisin family of serine proteases. They stand out among proteases since they attack the keratin residues and hence find application in developing cost-effective feather by-products for feed and fertilizers. Their application can also be extended to detergent and leather industries where they serve as specialty enzymes. Besides, they also find application in wool and silk cleaning; in the leather industry, better dehairing potential of these enzymes has led to the development of greener hair-saving dehairing technology and personal care products. Further, their prospective application in the challenging field of prion degradation would revolutionize the protease world in the near future.

571 citations

Journal ArticleDOI
TL;DR: In this article, the more important aspects of this process with particular emphasis on the microbiological aspects are analyzed, and some attention is also given to hygienic and sanitary implications as well as considerations on plant design.

486 citations

Journal ArticleDOI
TL;DR: Keratinases are exciting proteolytic enzymes that display the capability to degrade the insoluble protein keratin and their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling.
Abstract: Keratinases are exciting proteolytic enzymes that display the capability to degrade the insoluble protein keratin. These enzymes are produced by diverse microorganisms belonging to the Eucarya, Bacteria, and Archea domains. Keratinases display a great diversity in their biochemical and biophysical properties. Most keratinases are optimally active at neutral to alkaline pH and 40–60°C, but examples of microbial keratinolysis at alkalophilic and thermophilic conditions have been well documented. Several keratinases have been associated to the subtilisin family of serine-type proteases by analysis of their protein sequences. Studies with specific substrates and inhibitors indicated that keratinases are often serine or metalloproteases with preference for hydrophobic and aromatic residues at the P1 position. Keratinolytic enzymes have several current and potential applications in agroindustrial, pharmaceutical, and biomedical fields. Their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling.

388 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of insufficiently-matured compost on the soil-plant system are studied, and the criteria and methods proposed for the determination of compost maturity are described.

374 citations