Keratin biofilm from chicken feathers

Abstract

Keratin is an important biomaterial for industrial applications. About 90% of keratin is found in chicken feathers. Previous study showed that solid-state fermentation of keratinase by Bacillus sp. MD24 using chicken feathers a sole carbon and nitrogen source produced micro-keratin as a solid by-product. However, soluble by-product which most probably contained soluble keratin was not yet studied. This paper reports our investigation in soluble keratin in liquid by-product as possible raw material to generate biofilm. Fermentation of keratinase was done for 10 consecutive days by Bacillus sp. MD24 and liquid by-product was separated from solid by-product by centrifugation at 5000 rpm. The size of soluble keratin was examined by particle size analyser (PSA). The soluble keratin was filmed and the film was characterized using Fourier Transform Infrared Spectroscopy (FTIR) and film surface was analysed using Scanning Electron Microscopy (SEM). Dissolution of keratin using ionic liquids 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) and 1-Ethyl-3-methylimidazolium acetate ([EMIM]Ac) was done as alternative keratin degradation process. Dissolution was performed under nitrogen atmosphere at 130 °C for 7 hours. Insoluble fraction was recovered by addition of water. Keratin biofilm was generated and FTIR spectra indicated of absorption bands which were assigned to the peptide bonds (-CONH). The bands exhibited the presence of protein. There were no much difference on surface structure between keratin biofilm produced from soluble keratin by-product and dissolved keratin produced by dissolution using ionic liquid.