ABSTRACT
Alkaline proteases from the viscera of the striped seabream (Lithognathus mormyrus) were extracted and characterized. Interestingly, the crude enzyme was active over a wide range of pH from 6.0 to 11.0, with an optimum pH at the range of 8.0-10.0. In addition, the crude protease was stable over a broad pH range (5.0-12.0). The optimum temperature for enzyme activity was 50 °C. The crude alkaline proteases showed stability towards various surfactants and bleach agents and compatibility with some commercial detergents. It was stable towards several organic solvents and retained more than 50% of its original activity after 30 days of incubation at 30 °C in the presence of 25% (v/v) dimethyl sulfoxide, N,N-dimethylformamide, diethyl ether, and hexane. The crude enzyme extract was also tested for shrimp waste deproteinization in the preparation of chitin. The protein removal with a ratio enzyme/substrate of 10 was about 79%.
Subject(s)
Bacterial Proteins/metabolism , Biotechnology/methods , Detergents/metabolism , Endopeptidases/metabolism , Fish Proteins/metabolism , Recycling/methods , Sea Bream/metabolism , Viscera/enzymology , Animals , Bacterial Proteins/chemistry , Chitin/biosynthesis , Decapoda/metabolism , Detergents/chemistry , Electrophoresis, Polyacrylamide Gel , Endopeptidases/chemistry , Enzyme Stability , Hydrogen-Ion Concentration , Solvents/chemistry , Temperature , Waste ProductsABSTRACT
This study is concerned with the co-production of alkaline proteases and thermostable alpha-amylase by some feather-degrading Bacillus strains: B. mojavensis A21, B. licheniformis NH1, B. subtilis A26, B. amyloliquefaciens An6 and B. pumilus A1. All strains produced both enzymes, except B. pumilus A1, which did not exhibit amylolytic activity. The best enzyme co-production was obtained by the NH1 strain when chicken feathers were used as nitrogen and carbon sources in the fermentation medium. The higher co-production of both enzymes by B. licheniformis NH1 strain was achieved in the presence of 7.5 g/l chicken feathers and 1 g/l yeast extract. Strong catabolic repression on protease and alpha-amylase production was observed with glucose. Addition of 0.5% glucose to the feather medium suppressed enzyme production by B. licheniformis NH1. The growth of B. licheniformis NH1 using chicken feathers as nitrogen and carbon sources resulted in its complete degradation after 24 h of incubation at 37 degrees C. However, maximum protease and amylase activities were attained after 30 h and 48 h, respectively. Proteolytic activity profiles of NH1 enzymatic preparation grown on chicken feather or casein-based medium are different. As far as we know, this is the first contribution towards the co-production of alpha-amylase and proteases using keratinous waste. Strain NH1 shows potential use for biotechnological processes involving keratin hydrolysis and industrial alpha-amylase and proteases co-production. Thus, the utilization of chicken feathers may result in a cost-effective process suitable for large-scale production.
Subject(s)
Bacillus/enzymology , Bacterial Proteins/biosynthesis , Endopeptidases/biosynthesis , Feathers/metabolism , Industrial Microbiology/methods , alpha-Amylases/biosynthesis , Animals , Bacillus/growth & development , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Chickens , Endopeptidases/chemistry , Endopeptidases/genetics , Enzyme Stability , Fermentation , Hydrolysis , Keratins/metabolism , Substrate Specificity , alpha-Amylases/chemistry , alpha-Amylases/geneticsABSTRACT
The stability of crude extracellular protease produced by Bacillus licheniformis RP1, isolated from polluted water, in various solid laundry detergents was investigated. The enzyme had an optimum pH and temperature at pH 10.0-11.0 and 65-70 degrees C. Enzyme activity was inhibited by PMSF, suggesting that the preparation contains a serine-protease. The alkaline protease showed extreme stability towards non-ionic (5% Tween 20% and 5% Triton X-100) and anionic (0.5% SDS) surfactants, which retained 100% and above 73%, respectively, of its initial activity after preincubation 60 min at 40 degrees C. The RP1 protease showed excellent stability and compatibility with a wide range of commercial solid detergents at temperatures from 40 to 50 degrees C, suggesting its further application in detergent industry. The enzyme retained 95% of its initial activity with Ariel followed by Axion (94%) then Dixan (93.5%) after preincubation 60 min at 40 degrees C in the presence of 7 mg/ml of detergents. In the presence of Nadhif and New Det, the enzyme retained about 83.5% of the original activity. The effects of additives such as maltodextrin, sucrose and PEG 4000 on the stability of the enzyme during spray-drying and during subsequent storage in New Det detergent were also examined. All additives tested enhanced stability of the enzyme.
