| Summary: | 碩士 === 國立交通大學 === 分子醫學與生物工程研究所 === 98 === Biodiesel produced from animal fats and vegetable oils generates about 10% (w/w) glycerol. The excess glycerol becomes an environmental problem because it cannot be disposed as a waste. In this study, in order to enhance glycerol utilization, glycerol dehydrogenase (gldA), dihydroxyacetone kinase (dhaK) and glycerol-3-phosphate dehydrogenase (glpD) involved in glycerol metabolism were cloned on the overexpression plasmids. The results revealed that ethanol production from E. coli harboring gldA and dhaK was 3-fold higher than that of wild-type in anaerobic condition with sodium nitrate as electron acceptor. Moreover, E. coli can produce the highest ethanol under flow rate of 10 mL/min air and the presence of yeast extract. Coexpression of gldA , dhaK and glpD genes was conducted for ethanol fermentation. The result showed that ethanol production in optimal condition was 7-fold higher than that of wild type in the absence of yeast extract and anaerobic fermentation. Therefore , we have successfully constructed the plasmids harboring gldA , dhak and glpD genes in E. coli and demonstrated the optimal fermentative condition in glycerol metabolism with nitrate as electron acceptor.
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