Feather degradation potential of Stenotrophomonas maltophilia KB13 and feather protein hydrolysate (FPH) mediated reduction of hexavalent chromium.

Khushboo Bhange,Renu Bhatt,Venkatesh Chaturvedi

doi:10.1007/s13205-016-0370-5

Khushboo Bhange, Renu Bhatt + Show 1 more

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https://doi.org/10.1007/s13205-016-0370-5

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Abstract

An efficient keratinolytic strain of Stenorophomonas maltophilia KB13 was isolated from feather disposal site of Bilaspur, Chhattisgarh, India. The strain could metabolize 10 g/l chicken feathers as sole source of carbon and nitrogen. Soluble protein, amino acid, and cysteine content were found to be maximum (690.6 ± 8.7, 688.9 ± 9.12 and 21 ± 0.36 µg/ml, respectively) at late logarithmic phase of growth. Protease and keratinase activity reached its maximum level (103.26 ± 7.09 and 178.5 ± 9.10 U/ml) at the 4th day of incubation. The feather protein hydrolysate (FPH) obtained after degradation of chicken feathers was utilized to reduce hexavalent chromium. About 78.4 ± 2.4 and 63.6 ± 2.2 % reduction of 50 and 100 mg/l Cr(VI), respectively, was observed after 60 min of incubation with FPH. Further, there was no effect of autoclaved FPH on Cr(VI) reduction indicating that any bacterial enzyme was not involved in reduction process. Cr(VI) reduction was significantly inhibited by 10 mm Hg2+ ions indicating the role of sulfur-containing amino acids in reduction process. FTIR analysis confirmed that chromium reduction occurred due to oxidation of amino acids cysteine and cystine. This study shows that FPH arising after feather degradation can be employed as a potential candidate for the reduction of hexavalant chromium.

Highlights

Feathers are considered as a potent waste generated in large amount by various poultry industries around the world
There was no effect of autoclaved feather protein hydrolysate (FPH) on Cr(VI) reduction indicating that any bacterial enzyme was not involved in reduction process
Eight potential keratinolytic strains were isolated from soil samples collected from feather disposal site on the basis of enrichment technique in minimal medium containing chicken feathers (10 g/l) as sole carbon and nitrogen source

Summary

Introduction

Feathers are considered as a potent waste generated in large amount by various poultry industries around the world. Feathers consist largely of insoluble protein keratin, which contains high degree of cross linking by disulfide bonds, hydrogen bonding, and hydrophobic interactions (Jeong et al 2010). These interactions present in keratin make it highly recalcitrant in nature and its accumulation creates serious environmental concern. The hydrolysis of feathers by keratinolytic microorganisms represents alternative method to reduce energy loss and environmental pollution load (Fang et al 2013). Actinomycetes, and fungi are known to produce keratinolytic enzymes to degrade keratin and to metabolize it as carbon and nitrogen source (Tiwary and Gupta 2010). Most researches on microbial keratinases have been reported on Gram-positive bacteria, such as Streptomyces spp. Some Gram-negative bacteria, such as Chryseobacterium sp. (Riffel et al 2007), Aeromonas hydrophila K12, Stenotrophomonas maltophia (Yamamura et al 2002; Jeong et al 2010; Fang et al 2013), Serratia marcescens P3 (Bach et al 2012), and Pseudomonas

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