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عزل وتشخيص بكتريا Bacillus cereus واستعمالها في انتاج متعدد هيدروكسي البيوترات == Isolation and Identification of Bacillus cereus Bacteria and Using in Polyhydroxybutyrate Productio
Author name:
شيماء ذياب جدوع السهلاني
Supervisor name:
امال كاظم غضبان الاسدي
General topic:
Agricultural sciences
Specific topic:
Food
Degree:
Doctorate
University:
University Of Basrah - Faculty Of Agriculture
Language:
Arabic
University location:
Basrah
First pages:
31T1813 - p.pdf
Abstract:
Forty three local bacterial isolates were obtained after heating treatment for different sources collected from many places in Basra government. Included : Vegetables, Fruit, Pastry (cakes), Legumes, Soils, Sand, Animal manure, the papyrus plant, milk, water liquefaction and sewage water. Primary screening for the isolates by Sudan black B dye only. 22 isolates were chosen with strong staining, and the identification of all the isolates revealed were belong to genus Bacillus by studying microscopic and biochemical tests. They were : 4 isolates Bacillus cereus, 2 isolates Bacillus firmus, 2 isolates Bacillus lichenformis , 3 isolates Bacillus megaterium, 4 isolates Bacillus mycoides , 3 isolates Bacillus pumilus and 4 isolates Bacillus subtilis.Secondary screening of these isolates was Polyhydroxybutyrate (PHB) produced, Bacillus cereus B5 given 2.4 g / L the highest production of PHB. A PCR technique was used for 16S rRNA test and detecting the gene of PHB production in Bacillus cereus B5.The highest PHB production from Bacillus cereus B5 was 6.2 g / L, biomass 8.4 g / L and yield 73.8% the by using optimum conditions : incubation temperature 35̊ C, for 48 hours aerobically by using shaking incubator for 150 RPM/ min, 2% inoculum volume, the pH was adjusted to 7, and the production media where contained 1% glucose as carbon source and peptone as a nitrogen source. 3% have dated juice was the best substitute for glucose as carbon source, it gave 7.11 g PHB / L and the yield 79 %.Analysis with FT - IR was showed, that PHB produced from date juice media had a peak at 1723 cm - 1 this means it belong to an esterpolymers group. And GC - MS showed 12 compounds produce from analyzing PHB as short chains of fatty acids.The properties of PHB produced from date juice media were : The degradation temperature was 312̊ C, the percentage of crystallization was 60%, molecular weight was 423.674 KDa., permeability of water vapor was 56.2 ×10 - 8 g / Pa.s.m2, tensile strength was 24.9 MPa, the blend 40% polyethyleneglycol as plasticized with PHB increased the percentage of elongation to 8.7%. PHB is non - toxic and without hemolysis on human blood.Studying biodegradation of the plastic films of PHB by using bacterial isolates were E. coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus cereus in petri dish showed that all isolates can degrade PHB, biodegradation in soil and at soil surface was 100% after 28 days.PHB packages increased the shelf life of strawberries and grapes after storage for 15 days, compared with polyethylene packages, and It was reduced the numbers of microorganisms in butter, the percentage of free fatty acids and peroxide value compared with butter with polyethylene after 15 days
