Biochemical characterization of an alkaline surfactant-stable keratinase from a new keratinase producer, Bacillus zhangz
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ORIGINAL PAPER
Biochemical characterization of an alkaline surfactant‑stable keratinase from a new keratinase producer, Bacillus zhangzhouensis Roghyeh Moridshahi1 · Masoumeh Bahreini1 · Mohammadreza Sharifmoghaddam1 · Ahmad Asoodeh2 Received: 29 February 2020 / Accepted: 26 June 2020 © Springer Japan KK, part of Springer Nature 2020
Abstract A new keratinase producer, Bacillus sp. BK111, isolated from a poultry feather was identified as Bacillus zhangzhouensis, which is the first report for its keratinolytic activity. The keratinase production was optimized, followed by the enzyme purification and characterization using biochemical assays. A 2.34-fold increase was observed in the enzyme production under optimized conditions. The enzyme was characterized as a serine protease with 42 kDa molecular weight, stable in a wide range of temperature and pH with maximum keratinolytic activity at 60 °C and pH 9.5. The enzyme had a wide range of different substrates with the best performance on the feather meal substrate. Metal ions of Ca2+, K+, Na+ and Mn2+ enhanced the enzyme activity. The enzyme showed a great deal of stability in the presence of ethanol, methanol, acetone, 2-propanol, dimethyl sulfoxide, Tween-80 and Triton X-100. Dithiothreitol (DTT), as a reducing agent, caused a twofold increase in keratinolytic activity. The half-life of the enzyme at optimum temperature was calculated to be 125 min and the ratio of keratinolytic:caseinolytic for the enzyme was 0.8. Our results showed the remarkable features of the enzyme that make it suitable for biotechnological usages. Keywords Feather biodegradation · Keratinase · Optimization · Characterization · Bacillus zhangzhouensis
Introduction Feather, a potential choice for industrial applications, is produced and accumulated daily as waste by poultry industries which reaches millions of tons annually (Demir et al. 2015; Brandelli et al. 2015). Feather contains 90% keratin protein, one of a family of fibrous insoluble structural proteins. Keratin is a component of epidermal and skeletal Communicated by I. Cann. * Masoumeh Bahreini [email protected] Roghyeh Moridshahi [email protected] Mohammadreza Sharifmoghaddam [email protected] Ahmad Asoodeh [email protected] 1
Department of Biology, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
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tissue, which is a hard fiber protein with many disulfides, hydrogen and hydrophobic bonds conferring resistance to proteolytic hydrolysis (Tatineni et al. 2008; Lee and Baden 1975). Owing to its hard and insoluble structure, keratin is slowly degraded and consequently, accumulated in nature as a hazardous waste (Khardenavis et al. 2009). Today, feather is converted into feather meal using chemical or thermal processes. However, these processes are expensive, need highenergy consumption and decrease the amount of essential amino acids (Gupta and Ramnani 2006). Therefore, microbial hydrolysis is suggested as an
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