Thermophilic protease production by Streptomyces sp. 594 in submerged and solid-state fermentations using feather meal.

Aims: Protease production by Streptomyces sp. 594 in submerged (SF) and solid-state fermentation (SSF) using feather meal, an industrial poultry residue, and partial characterization of the crude enzyme.
Methods and Results: Streptomyces sp. 594 produced proteases in SF (7.2 +/- 0.2 U ml(-1)) and SSF (15.5 +/- 0.41 U g(-1)), with pH increase in both media. Considering protease activity, values obtained in the liquid extract after SSF (6.3 +/- 0.17 U ml(-1)) were lower than those from SF. The proteases, which belong to serine and metalloproteinase classes, were active over a wide range of pH (5.0-10.0) and high temperatures (55-80 degrees C). Strain 594 was also able to degrade feather in agar and liquid media. Keratinase activity (80 U l(-1)) also confirmed the keratin degrading capacity of this streptomycete.
Conclusions: Proteases produced using residues from poultry industry have shown interesting properties for industrial purposes.
Significance and Impact of the Study: As far as we are concerned, this is the first contribution towards the production of thermophilic protease by a streptomycete in SSF using a keratinous waste.