Abstract
This research was carried out to determine the optimal environmental and nutritional factors for amylase production and its activity by bacterial strains Bacillus amyloliquefaciens as well as to evaluate the kinetic characterization of the produced α-amylase. From the obtained results showed that the optimum pH, inoculum size, fermentation period, incubation temperature, carbon and nitrogen sources for produced glucose and amylase activity were 7.0, 1500 μl /ml, 72 h, 37oC, starch and tryptone, respectively when the basal broth medium was used as a fermentation medium rather than the using of starch broth medium for the production of α-amylase. In addition, data showed that the shaking method was better than the static one for amylase production. Moreover, the optimal conditions for fermentation process gave a higher records of produced glucose and amylase activity rather than each factor individually. The values of amylase activity, protein content and specific amylase activity were 697.60 U/ml, 57.14 mg/ ml and 12.21U /mg protein, respectively.
Concerning the factors affecting on produced α- amylase activity were evaluated. From the obtained results , the optimum temperature and pH values of the produced α-amylase from Bacillus amyloliquefaciens were found to be 65 oC and 6.0, respectively and the reaction activity were reached their maximum values were 15.46 U/ml /min for temperature and 18.8 U/ml/min for pH. The Vmax and Km values of the production enzyme under investigation were determined by incubation fixed amount of enzyme with varied concentrations of soluble starch at 65 oC , pH 6.0 and 15 min were 32.3 U/ml/min and 1.596 ml/100 ml, respectively . On the other hand, the obtained resulted indicated that the metal ion concentration of 1 mM had a greater effect on enzyme activities than 5 mM. The relative activities of the produced α-amylase were activated by Fe3+, Cu2+ and Ca2+ at 1 mM, but strongly inhibited by Mn2+ and Ni2+ at both 1 mM and 5 mM concentrations.
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