Keratinase production from a thermophilic actinomycete strain Cpt29 newly isolated from poultry compost

摘要

Aim. The present study reports the screening and identification of the thermophilic actinomycete strain Cpt29 isolated from poultry compost for keratinases production, the characterization and optimization of enzyme production, the ability of this strain to accomplish the whole keratin-degradation process of various keratinacious wastes. Methods. From 32 isolates of thermophilic actinomycetes recently isolated from poultry compost in Annaba (East of Algeria), one of them, the Cpt29 strain produced high amount of extracellular proteases as indicated by large halo on skim milk agar. The isolate exhibited high keratinase production when grown in chicken-feather meal media. On the basis of biochemical and physiological properties the select strain Cpt29 was identified and belonged to the Actinomadura genus. This strain was then optimized for keratinase enzyme production and chicken feather degradation, complete feather degradation by Actinomadura sp Cpt29 was achieved within 7 days of cultivation. Cultural and environmental conditions for keratinase production by this strain were also studied. Results. The highest enzyme production by this strain was obtained at pH 8.5, a temperature of 45°C after 7 days of incubation. The presence of chicken-feather meal as a sol carbon and nitrogen source in the medium induced the highest production of keratinase (80.27 IU/mL). The production of the enzyme was enhanced when the culture medium was supplemented with galactose (0.6%), yeast extract (1%), and dipotassium hydrogen phosphate (0.1%). After optimization of various production parameters, an increase of nearly three-fold in keratinase production was achieved. Conclusion. Thus the present study proved that the thermophilic actinomycete strain Actinomadura sp Cpt29 presented high keratinolytic activity, and was very effective in feather degradation, providing potential use for biotechnological processes of keratin hydrolysis.