الفهرس 
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Abstract
H 6. English Summary In the current work, we studied Microbiological and Biochemical Studies on Alpha amylase Enzyme Produced from Streptomycetes. Thirty-seven random Streptomycetes isolates were isolated from soil habitats. The maximum number of Streptomycetes isolates were found in Dakahlia, followed by Gharbia and Giza. Streptomycetes isolates were chosen based on the distinctive colony morphological characters, which is often spherical, convex, and has deeply rooted development into the medium. Typically, dry, powdery spore masses cover the surface of the colonies.
The screening of Alpha amylase from the obtained isolates of Streptomycetes is tested using a rapid plate assay test technique revealed that only twelve Streptomycetes isolates were distinguished by the presence of Clear Zone around their colonial growth as evidence and have highest ability for the production of extracellular alpha- amylase. were screened quantitatively for production of alpha- amylase. Protein estimation, enzyme formation and specific activity were measured for every isolate and illustrated that isolate (D10) showed that was the highest specific activity. isolates (D10) showed straight flexuous spore chain morphology with smooth spore surface ornamentation. While color of spore mass was gray while, Pigmentation of substrate mycelium was grayish white.
The morphological identities of Streptomyces sp. have been confirmed from the results of molecular sequences of the amplified 16S rRNA gene.
Some factors affected on the production of alpha amylase and the maximum production (910.43±8.77 U/ml) was done after 7 days, pH 7, 30 ºC, Starch was supported maximal enzyme yield and arabinose was the least effective as a carbon source and peptone was supported maximal enzyme output. while, ammonium oxalate was the least effective as a nitrogen source.
The enzyme displayed stability in the pH range of 6.5 to 10.0. The effect of pH influence on enzyme stability. The effect of pH on alpha amylase activity and stability were studied at different pH levels ranging from 3.0 to 11.0. The following buffers were used at concentrations of 100 mM: sodium citrate buffer for pHs ranging from 3.0 to 4.5, sodium acetate buffer for pHs ranging from 4.5 to 6.0, sodium phosphate buffer for pHs ranging from 6.0 to 7.5, Tris-HCl buffer for pHs ranging from 5.5 to 9.0, and glycine-NaOH buffer for pHs ranging from 9.0 to 11.00.
the perfect enzyme activity temperature was revealed the enzyme activity evaluated at 55 oC was found to be at its highest and was therefore considered to be the ideal temperature for activity the temperature stability, the enzyme was stable at temperatures 70 oC (for 30 minutes).
Only Hg2+, Cu2+, Zn and Ba2+ among the ions examined showed a significant reduction of activity, with Na+, Mg2+, Mn2+, and Co2+ serving as an inducer at both 2 and 5 mM.
The kinetic parameters of purified alpha amylase, such as the Michalis-Menten constant (Km) and maximum velocity (Vmax), were determined in this experiment by incubating the enzyme with different concentrations of each substrate in the range of (2.5 to 15 mM) under optimum assay conditions. A Lineweaver-Burk plot was used to calculate the apparent Km and Vmax of purified enzyme.