| Summary: | 碩士 === 輔仁大學 === 生命科學系碩士班 === 92 === The purple nonsulfur bacteria Rhodobacter sphaeroides FJ1 was isolated from waste water and produced high levels of polyhydroxybutyrate ( PHB ). Three genes, phbA ( -ketothiolase ), phbB ( acetoacetyl-CoA reductase ) and phbC ( PHB synthase ) which were involved in the PHB production were cloned from R. sphaeroides FJ1. Unlikely Ralstonia eutropha, the phbC genes encoding 601 amino acids in R. sphaeroides FJ1 are not linked with the phbAB gene. To construct pHEV65 and pERI27, there were three ORFs near the phbC gene possibly related to PHB synthesis. Orf424 which is located upstream of phbC of R. sphaeroides FJ1 is similar to phbZ of R. capsulatus and P. denitrificans ( 75 % and 71 % identity ), and hence, we named its phbZ gene. Orf150 and orf185 were located downstream of phbC gene and denominated to phbP and phbR gene, forms the phbZ-C-P-R locus and phbA-B cluster in R. sphaeroides FJ1. Expression of PhbC was observed in Escherichia coli carrying a 67 kDa protein and PHB synthase accumulates in R. sphaeroides FJ1 was determined by immunoblotting. The results indicated the PHB synthase was a constitutive protein whether in different growth condition. Utilizing low-cost waste water and fed-batch methods, accumulated to 60 % of the dry weight when R. sphaeroides FJ1 was grown in media containing excess carbon and limited nitrogen. To Indicate R. sphaeroides FJ1 can utilize waste water to grow and product PHB.
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