New keratinolytic bacteria in valorization of chicken feather waste

Abstract

There is an increasing demand for cost-effective and ecologically-friendly methods for valorization of poultry feather waste, in which keratinolytic bacteria present a great potential. Feather-degrading bacteria were isolated from living poultry and a single strain, identified as Kocuria rhizophila p3-3, exhibited significant keratinolytic properties. The bacterial strain effectively degraded up to 52% of chicken feathers during 4 days of culture at 25 °C. Zymographic analysis revealed the presence of two dominating proteolytic enzymes in the culture fluid. Culture conditions were optimized in order to maximize the liberation of soluble proteins and free amino acids. A two-step procedure was used, comprising a Plackett–Burman screening design, followed by a Box–Behnken design. Concentration of feather substrate, MgSO4 and KH2PO4 were the most influential parameters for the accumulation of soluble proteins in culture K. rhizophila p3-3, while feathers and MgSO4 also affected the concentration of amino acids. The resultant raw hydrolysate supernatant, prior to and after additional treatments, was rich in phenylalanine, histidine, arginine and aspartic acid. Additionally the hydrolysate exhibited radical-scavenging activity and ferric reducing power.Electronic supplementary materialThe online version of this article (10.1186/s13568-018-0538-y) contains supplementary material, which is available to authorized users.

Citrobacter diversus-derived keratinases and their potential application as detergent-compatible cloth-cleaning agents

“…As a result of microbial growth and metabolism of amino acids derived from protein hydrolysis, increases in turbidity and pH of the medium were observed, demonstrating the ability of this bacterium to efficiently degrade keratin [30]. The keratin degradation ability of C. diversus demonstrated in this study (~85% in 36 h) was higher than that of the bacterium Kocuria rhizophila strain p3-3, which was previously reported to degrade only 52% of chicken feathers in 96 h of fermentation in submerged culture [31]. In contrast, the keratin degradation ability of C. diversus was similar to that of the Alcaligenes sp.…”

Co-production of Proteases and Bioactive Protein Hydrolysates from Bioprocessing of Feather Meal

“…Reducing power and radical scavenging were also displayed by feather hydrolysates produced by Bacillus sp. MPTK6 [37], and Kocuria rhizophila p3-3 [38]. Such potentials were also verified for hydrolysates of delimed tannery fleshings obtained by 4-day cultivations with Enterococcus faecium NCIM5335 [39], for shrimp shell waste hydrolysates produced by P. aeruginosa A2 [40].…”

Optimization and validation of keratinase production by Bacillus aerius NSMk2 in a stirred tank reactor using response surface methodology

“…[25]. Laba et al [26] and Mamangey et al [27] reported keratinase production by Kocuria rhizophila and Azotobacter chroococcum at 180 rpm. Optimal keratinase production by Actinomadura keratinilytica [28], Bacillus amyloliquefaciens [29] and Chryseobacterium sediminis [30] has been reported at 200 rpm, while optimal keratinase production from Bacillus licheniformis has been reported at 250 rpm [31].…”