Abstract
Three Bacillus species (B. subtilis LFB-FIOCRUZ 1270, B. subtilis LFB-FIOCRUZ 1273, and B. licheniformis LFB-FIOCRUZ 1274), isolated from the poultry industry, were evaluated for keratinase production using feathers or feather meal as the sole carbon and nitrogen sources in a submerged fermentation. The three Bacillus spp. produced extracellular keratinases and peptidases after 7 days. Feather meal was the best substrate for keratinase and peptidase production in B. subtilis 1273, with 412 U/mL and 463 U/ml. The three strains were able to degrade feather meal (62–75%) and feather (40–95%) producing 3.9–4.4 mg/ml of soluble protein in feather meal medium and 1.9–3.3 mg/ml when feather medium was used. The three strains produced serine peptidases with keratinase and gelatinase activity. B. subtilis 1273 was the strain which exhibited the highest enzymatic activity.
Highlights
Feather waste is a byproduct of the domestic poultry industry and is 90% keratin [1, 2]
Extracellular keratinase and peptidases were obtained after growth of the Bacillus sp. on the culture medium containing feathers or feather meal as the sole carbon and nitrogen sources
Feather meal was the best substrate for keratinase production with B. subtilis 1270
Summary
Feather waste is a byproduct of the domestic poultry industry and is 90% keratin [1, 2]. Keratin is an insoluble protein and is resistant to degradation by common peptidases, such as trypsin, pepsin, and papain [4, 5]. This resistance is due to the constituent amino acid composition and configuration that provide structural rigidity. The mechanical stability of keratin and its resistance to biochemical degradation depend on the tightly packed protein chains in α-helix (α-keratin) and β-sheet (β-keratin) structures. These structures are cross-linking by disulfide bridges in cystines residues [3, 4, 6]
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