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1. Feathers are recalcitrant protein-rich wastes produced in huge amounts by poultry processing for meat production. Hence, feather bioconversion and protease production by Bacillus sp. CL18 were investigated. 2. Bacillus sp. CL18 demonstrated a remarkable feather-degrading potential. Through cultivations on feather broth (10 g l feathers), 94.5% ± 3% of whole feathers were degraded after 4 d. Increases in soluble protein contents were observed and protease production was maximal also at d 4. This strain produced diverse proteolytic enzymes during growth. 3. Crude protease displayed optimal activity at 55°C (50-62°C), pH 8.0 (7.0-9.0) and a low thermal stability. Proteolytic activity increased in the presence of Ca, Mg, Triton X-100, Tween 20 and dimethyl sulphoxide. Inhibition profile indicated that crude protease contains, mainly, serine proteases. Enzyme preparation hydrolysed mainly casein and soy protein isolate. 4. The keratinolytic capacity of Bacillus sp. CL18 at moderate temperatures (30°C) might be appropriate for feather conversion, resulting in protein hydrolysates and proteolytic enzymes. Proteases are postulated to be added-value products that can be obtained from such a bioprocess.

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Eighteen bacterial strains were isolated from soil of an urban area located in a transition zone between the Atlantic Forest and Pampa biomes, in southern Brazil. These strains were screened for cellulolytic, lipolytic and proteolytic potentials. Eleven isolates (61%) were able to produce cellulolytic enzymes on carboxymethylcellulose (CMC) agar plates, 14 isolates (78%) were proteolytic on skim milk agar plates, and all isolates demonstrated lipolytic/esterolytic potential on tributyrin agar (TBA) plates. From the 18 bacteria, nine (50%) were shown to produce the three investigated enzyme activities. Selected isolates were then evaluated for growth and enzyme production at different conditions of temperature and pH on CMC agar, TBA, and feather meal agar plates. As a general trend, growth and hydrolysis zones were observed at pH 6.0–9.0 and 30–37