Isolation and characterization of a poultry feather-degrading Bacillus spp strain

Sample soils from a poultry plant were inoculated in enrichment medium with feathers as the major source of carbon and energy with the purpose of favoring the development of microorganisms with keratinolityc capacity. Colonies grown in nutrient agar plates streaks from enrichment medium were inoculated in tubes with saline medium with whole feathers and incubated at 40 degrees C in order to isolate feather degrading strains. It selected the strain LPB-2 which produced highest feather degradation (3 days). The microorganism was a Gram positive rod (2.4 x 0.64 mu m) and was identified as Bacillus sp. Cultures of LPB-2 in 500 mL Erlenmeyer baffled flasks containing 20 g/L of feather medium showed optimum feather degradation, measured as free amino groups (GAL), in the range of 35-40 degrees C. Growth rate was estimated in 0.205 h(-1) with a maximum biomass of 1.6 g/L in 24 hours at 40 degrees C and 75 rpm. Under these conditions, proteolity C activity in fermentation broths attained 0.28 U/mL, and it was associated to microbial growth. GAL concentration and the amount of feather digestion followed similar trends, obtaining in 32 hours of cultivation 22 mmol/L and 35% respectively. The strain produced traces of citric, gluconic, malic, lactic, propioni C and butyric C acids.