Characterization and biotechnological study on microbial amylase production from local isolates / Wagiha Samir Abbas Elkalla ; Supervised Alaa Eldien M. S. Hosny , Yasser Elmohammady Ragab

Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

A number of 141 isolates were isolated from different samples collected from different sources allover Egypt. The screening was done by starch hydrolysis method. Identification of all isolates by classical methods revealed that they belonged to the genus Bacillus. Two strains of Bacillus were selected for further study based on their activity measured by starch iodine method. Optimum conditions for enzyme production were determined, using both starch iodine and DNS method. The maximum amylase production was generally reached after incubation for 48 hrs at a temperature of 37-45{u00B0}C, optimum pH of 6.8, and starch concentration 1 % in the production media. The addition of starch as an inducer increases amylase productivity compared to lactose, glucose, sucrose or fructose. The use of NaC₁, CaCl₂ and MgCl₂ as additives had no effect on the production of the enzyme while CuSO₄, FeSO₄, and FeC₃ sharply inhibited amylase production. Characterization of the crude enzyme revealed that the enzyme showed almost the same activity at room temperature and up to 60{u00B0}C, good thermal stability at temperature up to 100{u00B0}C and a pH range of 5 to10. Amylase production, by the two tested isolates, using submerged fermentation was higher than that obtained by solid state fermentation. Amylase productivity of the two isolates compared to a reference strain revealed that productivity of isolate1 was higher than isolate 2 and the reference strain.

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