title: Biodegradation of feather waste by extracellular keratinases and gelatinases from Bacillus spp.
abstract: In this study, three feather degrading bacterial strains were isolated from agroindustrial residues from a Brazilian poultry farm. Three Gram-positive, spore-forming, rod-shaped bacteria and were identified as B. subtilis 1271, B. licheniformis 1269 and B. cereus 1268 using biochemical, physiologic and molecular methods. These Bacillus spp. strains grew and produced keratinases and peptidases using chicken feather as the sole source of nitrogen and carbon. B. subtilis 1271 degraded feathers completely after 7 days at room temperature and produced the highest levels of keratinase (446 U ml(-1)). Feather hydrolysis resulted in the production of serine, glycine, glutamic acid, valine and leucine as the major amino acids. Enzymography and zymography analyses demonstrated that enzymatic extracts from the Bacillus spp. effectively degraded keratin and gelatin substrates as well as, casein, hemoglobin and bovine serum albumin. Zymography showed that B. subtilis 1271 and B. licheniformis 1269 produced peptidases and keratinases in the 15-140 kDa range, and B. cereus produced a keratinase of ~200 kDa using feathers as the carbon and nitrogen source in culture medium. All peptidases and keratinases observed were inhibited by the serine specific peptidase inhibitor phenylmethylsulfonyl fluoride (PMSF). The optimum assay conditions of temperature and pH for keratinase activity were 40-50°C and pH 10.0 for all strains. For gelatinases the best temperature and pH ranges were 50-70°C and pH 7.0-11. These isolates have potential for the biodegradation of feather wastes and production of proteolytic enzymes using feather as a cheap and eco-friendly substrate.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia Prof. Paulo de Góes (IMPPG), Bloco I, Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, 21941-590, Brazil.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Mazotto
authors.forename: Ana Cristina N
authors.initials: AC
authors.lastname: de Melo
authors.forename: Andrew
authors.initials: A
authors.lastname: Macrae
authors.forename: Alexandre Soares
authors.initials: AS
authors.lastname: Rosado
authors.forename: Raquel
authors.initials: R
authors.lastname: Peixoto
authors.forename: Sabrina M L
authors.initials: SM
authors.lastname: Cedrola
authors.forename: Sônia
authors.initials: S
authors.lastname: Couri
authors.forename: Russolina B
authors.initials: RB
authors.lastname: Zingali
authors.forename: Ana Lúcia V
authors.initials: AL
authors.lastname: Villa
authors.forename: Leon
authors.initials: L
authors.lastname: Rabinovitch
authors.forename: Jeane Q
authors.initials: JQ
authors.lastname: Chaves
authors.forename: Alane B
authors.initials: AB
authors.lastname: Vermelho