الفهرس 
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Abstract
PHAs are an aliphatic microbial polyesters produced by a variety of bacteria. The most commonly occurring PHA is polyhydroxybutyrate (PHB). Alginate is a linear copolymer produced from Pseudomonas and Azotobacter. The aim of this work was isolation, identification of some local bacterial isolates and testing their for PHB and alginate production. Also, factors affecting PHB production by the active bacterium and spectroscopic analysis of PHB were studied.
This study divided into three parts : The first part : Isolation and Identification of the isolates produced biopolymers : Azotobacter, Azospirillum, Bacillus, Pseudomonas, Streptomyces and Alcaligenes were isolated from the rhizosphere of several plants. The isolates were purified and identified as 17 Azotobacter chroococcum, 8 Azospirillum lipoferum, 22 Alcaligenes eutrophus, 3 Alcaligenes latus, 3 Bacillus subtilis, 2 B. alvei, 2 B. cereus, 2 B. coagulans, 5 B. megaterium, 3 B. polymyxa, 4 B. thuringiensis. 2 Pseudomonas putida, 2 P. fluorescence, 2 P. aeruginosa 2 P. alcaligenes and 12 Streptomyces albus. Four isolates of Rhizobium leguminosarum, two isolates of R. meliloti and one isolate of R. japonicam were obtained from Microbiology Department, Fac. of Agric., Mansoura Univ.
The second part : Efficiency of the bacterial isolates for PHB and alginate production : For screening the most active isolates which can produce PHB and alginate, and to achieve this propose all isolates were cultivated in 250 ml Erlenmeyer flasks, each containing 50 ml of sterile different specific media and inoculated with standard inoculum. 1. PHB production : 17 isolates A. chroococcum were tested for PHB production and the best isolate was A. chroococcum No. 16 (0.78 g/l). 8 Azospirillum lipoferum were tested for PHB production and the best isolate of PHB production was A. lipoferum No. 5 (0.58 g/l). 25 isolates Alcaligenes eutrophus were tested for PHB production, the best isolate was A. eutrophus No. 21 (0.52 g/l). 21 Bacillus, the best isolate was B. megaterium No. 5 (0.16 g/l). 8 isolates Pseudomonas putida, were tested and the best isolate was P. fluorescence No. 1 (0.30 g/l). 7 Rhizobium were tested and the best isolate was R. leguminosarum No. 3 (0.36 g/l). 12 isolates Streptomyces albus were tested. The best isolate was S. albus No. 10 (0.12 g/l). 2. Alginate production : The best isolate for alginate production was P. aeruginosa No. 2 (0.38 g/l), and Azotobacter chroococcum No. 14 (0.44 g/l).
The third part : 1- The influence of environmental conditions on the accumulation of PHB in Azotobacter chroococcum : The purpose of this part is to investigate the optimal conditions for PHB production by A. chroococcum No. 16 The experiments were carried out in factorial arrangement. The best time course was after 54 hours and the PHB production was 0.85 g PHB /l. The optimum initial pH was 7.5 and the PHB production was 1.06 g PHB /l. Different carbon sources were used for PHB production. The highest amount of PHB was obtained with glucose syrup being 1.76 g/l. The effect of glucose syrup (as total sugars) concentration on PHB production was studed. At 12.5 g/l sugar concentration PHB reached its maximum being 1.81 g/l. Different nitrogen sources were investigated. The highest growth and PHB production were obtained with NH4NO3 as a nitrogen source (6.54 g/l and 2.16 g/l, respectively). The effects of NH4NO3, K2HPO4, KH2PO4, NaCl, MgSO4.7H2O, CaSO4.2H2O, NaMoO4.2H2O and ferric citrate on PHB production were studied and the production were 2.66, 3.04, 3.12, 3.56, 3.74, 3.82, 3.80 and 3.82 g/l, respectively
2- The spectroscopic analysis of PHB polymer : IR spectroscopic analysis was done, the analysis of the spectrum of PHB was observed at 3400, 1639, 3018, 2978, 2842, 1216, 1044, 1164, 434 and 669-765δ, respectively, for (-OH) broad peak, (C=C) double bond, (≡C-H) acetylenic bond, (-CH3) methyl group, (-S-H) thiol weak adsorption, (≡C-O-C≡) ether, (-O-C-O), (C-C=O), sulfoxide and (F-Cl) haloalkanes. The present of ether-linkage give the polymer elasticity and flexibility. The chains have the C=O and CH3 groups in the amorphous regions is responsible for the good mechanical properties.