ISOLATION AND PRODUCTION OF POLY-?-HYDROXY BUTYRATES

Abstract

Polyhydroxybutyrates (PHB) are bio-plastics produced by many microorganisms under carbon rich conditions. PHBs are carbon storage compounds also known as Poly hydroxyalkanoates.PHB’s are high in molecular weight, polyester is accumulated as a storage carbon in many species of bacteria and is a biodegradable thermoplastic. Several gram-negative bacteria, including pseudomonas aeruginosa, have been employed for the efficient production of PHB. These gram negative bacteria can release endotoxin(pyrogen), which was in the form of lipopolysaccharides, from the cell wall (Raetz, 1993). Since PHB was most efficiently produced by gram-negative bacteria as described, the endotoxin levels present in the purified PHB should be examined can accumulate PHB in the form of multiple granules of 0.2 to0.5μm size. Pseudomonas species contains high PHB accumulating ability. Pseudomonas species are Gram negative, rodshaped aerobic bacteria Bacteria were isolated from native environment by culturing on nutrient agar and cetrimide agar media. When stained with Sudan Black Dye black colour granules are observed As a positive result. Polybeta-hydroxybutyrate can be further used for the production of Bio plastics. Microbial biosynthesis of PHB starts with the condensation of two molecules of acetylcoenzyme to give acetoacetyl-CoA which is subsequently reduced to hydroxybutyryl-CoA. This latter compound is then used as a monomer to polymerize. The microbial production of copolymers of 3- hydroxybutyrateand 3- hydroxyvalerate, with properties varying according to copolymer composition, must be considered. The production cost of PHB’s are very high when compared. to non-degradable plastics hence search for potential strains that accumulates high PHB’s