الفهرس 
AIM OF THE STUDYOnly 14 pages are availabe for public view
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Abstract
-Sixty bacterial isolates isolated from different sources.
-The PHA production ability was examined by Sudan black B and Nile blue Astains.
-The three most potent isolates were selected
-The three bacterial isolates were identified by biochemical and molecular methods as Bacillus flexus AESK1, Bacillus megaterium SMSE, and Bacillus iocasaemmas4.
-Plackett-Burman (PB) factorial design was used to screen the most optimum condition that would enable the bacterial isolates to produce more PHA.
-After determining the most optimized condition for the production of PHAwhich is detected by Plackett-Burman (PB) design and by using low-cost media containing molasses, The enhancement step was used to increase PHA production by adding ethanol70%, hydrogen peroxide, and a mixture(1:1) of ethanol and hydrogen peroxide as external stress factors at the bacterial stationary phase and determining which stress factor was best for each bacterial isolate to produce the most PHA, as Bacillus megaterium SMSE1gave 85% of PHA with ethanol 2 %compare to control test 23% of PHA. Bacillus flexus AESK1 produced the most PHA 41.43%, with ethanol 2 %, compared to the control test 13.27 %, and Bacillus iocasae mmas4 produced the most PHA 42.5 %with hydrogen peroxide 1 %compared to the control 10 %.
-After being exposed to the best medium condition and stress factor, each bacterial strain’s PHA was extracted and analyzed using FTIR, H1NMR, TGA, and DTA.
-It was determined that the PHA produced by all three isolates was a copolymer P (3HB-co-3-HV) [poly-3-hydroxy butyrate-poly-3-hydroxy valerate] with a thermal stability of about 200°C.
Inconclusion: During this study three local Egyptian bacterial isolates, recovered from garbage and sewage, were able to produce PHA and identified as Bacillus flexus AESK1, Bacillus megaterium SMSE, and Bacillus iocasaemmas4. The production of PHA was optimized using PB factorial design, and then this production was enhanced by adding stress factors during the stationary phase. This is the first record for the production of PHA by Bacillus iocasaemmas4.The produced polymer from the three bacterial isolates was characterized by FTIR, 1HNMR, TGA, and DTA.It was determined that the PHA was a co-polyester P (3HB-co-3-HV) that was thermally stable up to 200°C.