Isolation, identification, and characterization of a feather-degrading bacterium.
01 Jun 1990-Applied and Environmental Microbiology (American Society for Microbiology)-Vol. 56, Iss: 6, pp 1509-1515
TL;DR: A feather-degrading culture was enriched with isolates from a poultry waste digestor and adapted to grow with feathers as its primary source of carbon, sulfur, and energy, indicating a potential biotechnique for degradation and utilization of feather keratin.
Abstract: A feather-degrading culture was enriched with isolates from a poultry waste digestor and adapted to grow with feathers as its primary source of carbon, sulfur, and energy. Subsequently, a feather-hydrolytic, endospore-forming, motile, rod-shaped bacterium was isolated from the feather-degrading culture. The organism was Gram stain variable and catalase positive and demonstrated facultative growth at thermophilic temperatures. The optimum rate of growth in nutrient broth occurred at 45 to 50°C and at pH 7.5. Electron microscopy of the isolate showed internal crystals. The microorganism was identified as Bacillus licheniformis PWD-1. Growth on hammer-milled-feather medium of various substrate concentrations was determined by plate colony count. Maximum growth (approximately 109 cells per ml) at 50°C occurred 5 days postinoculation on 1% feather substrate. Feather hydrolysis was evidenced as free amino acids produced in the medium. The most efficient conditions for feather fermentation occurred during the incubation of 1 part feathers to 2 parts B. licheniformis PWD-1 culture (107 cells per ml) for 6 days at 50°C. These data indicate a potential biotechnique for degradation and utilization of feather keratin.
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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
Cites background from "Isolation, identification, and char..."
...This can be exemplified from the literature where keratinase is mainly produced during the late exponential or stationary phase of microbial growth (Williams et al. 1990; Cheng et al. 1995; Sangali and Brandelli 2000; Vidal et al. 2000; Kim et al. 2001; Ramnani and Gupta 2004; Thys et al. 2004),…...
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...As far as physical parameters for production are concerned, they are species-specific and thus vary with respect to the organism (Table 1) (Williams et al. 1990; Friedrich and Antranikian 1996; El-Naghy et al. 1998; Sangali and Brandelli 2000;Vidal et al. 2000; Rissen andAntranikian 2001; Rozs et…...
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...Most of the organisms are capable of using keratin as the sole source of carbon and nitrogen (Williams et al. 1990; El-Naghy et al. 1998; Lin et al. 1999; Szabo et al. 2000; Gousterova et al. 2005)....
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TL;DR: Supporting evidence of a nutritional (amino acid) upgrading sequel to diverse microbial treatments of feathers, and positive results obtained from growth studies in rats and chicks have been presented.
529 citations
TL;DR: The potential of anaerobic digestion for material recovery and energy production from poultry slaughtering by-products and wastes and the current experience of the anaerobia digestion treatment of these materials are reviewed.
489 citations
TL;DR: The purified keratinase hydrolyzes a broad range of substrates and displays higher proteolytic activity than most proteases and is a useful enzyme for promoting the hydrolysis of feather keratin and improving the digestibility of feather meal.
Abstract: A keratinase was isolated from the culture medium of feather-degrading Bacillus licheniformis PWD-1 by use of an assay of the hydrolysis of azokeratin. Membrane ultrafiltration and carboxymethyl cellulose ion-exchange and Sephadex G-75 gel chromatographies were used to purify the enzyme. The specific activity of the purified keratinase relative to that in the original medium was approximately 70-fold. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and Sephadex G-75 chromatography indicated that the purified keratinase is monomeric and has a molecular mass of 33 kDa. The optimum pH and the pI were determined to be 7.5 and 7.25, respectively. Under standard assay conditions, the apparent temperature optimum was 50°C. The enzyme is stable when stored at −20°C. The purified keratinase hydrolyzes a broad range of substrates and displays higher proteolytic activity than most proteases. In practical applications, keratinase is a useful enzyme for promoting the hydrolysis of feather keratin and improving the digestibility of feather meal. Images
363 citations
TL;DR: A serine protease from the keratin-degrading Streptomyces pactum DSM 40530 was purified by casein agarose affinity chromatography and showed high stereoselectivity and secondary specificity with different synthetic substrates.
Abstract: A serine protease from the keratin-degrading Streptomyces pactum DSM 40530 was purified by casein agarose affinity chromatography. The enzyme had a molecular weight of 30,000 and an isoelectric point of 8.5. The proteinase was optimally active in the pH range from 7 to 10 and at temperatures from 40 to 75 degrees C. The enzyme was specific for arginine and lysine at the P1 site and for phenylalanine and arginine at the P1' site. It showed a high stereoselectivity and secondary specificity with different synthetic substrates. The keratinolytic activity of the purified proteinase was examined by incubation with the insoluble substrates keratin azure, feather meal, and native and autoclaved chicken feather downs. The S. pactum proteinase was significantly more active than the various commercially available proteinases. After incubation with the purified proteinase, a rapid disintegration of whole feathers was observed. But even after several days of incubation with repeated addition of enzymes, less than 10% of the native keratin substrate was solubilized. In the presence of dithiothreitol, degradation was more than 70%.
344 citations
References
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TL;DR: A water-soluble (at pH 8) aromatic disulfide [5,5′-dithiobis(2-nitrobenzoic acid] has been synthesized and shown to be useful for determination of sulfhydryl groups.
23,232 citations
"Isolation, identification, and char..." refers methods in this paper
...The cultures were sampled daily for cell numbers by determining CFU on ball-milled-feather agar plates, and soluble sulfhydryl concentrations were determined by the method of Ellman (4), as modified by Shih et al....
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TL;DR: Do the microorganisms decompose native keratin during their growth on keratinaceous substrates, or do they grow at the expense of nonkeratinaceous nutrients that are usually present as minor constituents of such substrates?
Abstract: Keratin, by virtue of its insolubility and resistance to proteolytic enzymes, is not attacked by most living organisms. Nevertheless, keratin does not accumulate in nature and, therefore, biological agencies may be presumed to accomplish its removal. Several insects, including clothes moth larvae, carpet beetles, and chewing lice are known to digest keratin (Waterhouse, 1957). The common occurrence in nature of microorganisms that readily and, in some cases, preferably grow on keratinaceous substrates has supported the general belief that certain microorganisms can digest keratin. Classical examples of such microbes are the parasitic dermatophytes and the saprophytic Onygena equina (Ward, 1899). In addition, the literature contains numerour reports that the ability to decompose keratin is possessed by various other microorganisms, e.g., members of the genus Ctenomyces (Sen Gupta et al., 1950; White et al., 1950), Chytrids (Karling, 1948), Streptomyces albus (Hirschman et al., 1944), and an oral bacterium (Schatz et al., 1955). White et al. (1950) and Vanbreuseghem (1952) surveyed many species of molds for their ability to digest wool and hair, and concluded that only the dermatophytes and certain Ctenomyces species could \"attack\" keratin. Among the dermatophytes, strains of Microsporum gypseum have been reported to be especially active in the decomposition of keratin (Mandels et al., 1948; Page, 1950). A basic question involved in studies on microbial decomposition of keratin is: do the microorganisms decompose native keratin during their growth on keratinaceous substrates, or do they grow at the expense of nonkeratinaceous nutrients (fats, carbohydrates, and proteins) that are usually present as minor constituents of such substrates? In seeking an answer to this question,
200 citations
Additional excerpts
...18, 1958), Ctenomyces (14), and Streptomyces (9)....
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TL;DR: Amino acid content and in vitro protein digestibility and solubility of feather meal, as affected by varying lengths of processing time (30 to 70 min) and moisture content (50 to 70%), were studied by a multiple regression technique as mentioned in this paper.
152 citations
"Isolation, identification, and char..." refers background in this paper
...These treatment processes require significant energy and also destroy certain amino acids (10-12, 17)....
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TL;DR: Feather meal as the primary source of protein for the chick in practical rations was never as good as other protein feedstuffs used, and it was suggested that feather meal was being used as a source of non-specific nitrogen.
95 citations
"Isolation, identification, and char..." refers background in this paper
...Feather waste, generated in large quantities as a byproduct of commercial poultry processing, is nearly pure keratin protein (7)....
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TL;DR: A keratinolytic enzyme secreted by Streptomyces fradiae is shown to have the property of solubilizing more than one-third the weight of unaltered wool as discussed by the authors.
69 citations