| Summary: | 碩士 === 明志科技大學 === 生化工程研究所 === 100 === Taiwan is a highly energy-dependent country. In Taiwan, annual local demand for petro-diesel increased up to 4.4 billion liters. In order to reduce the reliance on fossil fuels, the Taiwanese government has begun to adjust relevant energy policy and to develop alternative energy resources. Biodiesel is a promising candidate that can be used in place of petro-diesel, because of a similar chemical structure and combustion efficiency with petro-diesel. Biodiesel is commonly produced by the transesterification or esterification of oil with short chain alcohols. Oil crops, waste oil, and oleaginous microorganisms are commonly used as feedstock for biodiesel production. However, biodiesel produced form those feedstocks cannot satisfy the annual demand for petro-diesel in Taiwan. In this study, microbial cell membrane was used as a novel feedstock for biodiesel production because of its similar chemical structure to that of triglyceride, a typical biodiesel precursor. Escherichia coli are used as the model strain because of a high growth rate and well developed genotype for the production of recombinant proteins. Esterification of E. coli cell membrane and methanol was catalyzed using sulfuric acid; and the production yield, which was affected by the reaction conditions, was optimized using response surface methodology. A maximal production yield of 5.36% was obtained at 105°C, at a catalyst/biomass mass ratio of 0.3, and after a reaction time of 120 min. The experimental results also show that biodiesel productivity using the proposed source is approximately 61.7 times the productivity of microalgae, indicating its potential applications including biodiesel production. For conventional heating, heat energy is
transferred to the reaction through convection and conduction from the surfaces of the reactor, but this type of heating is inefficient. Recently, microwave has been developed to provide an effective heat source for the reaction. Microwave radiation delivers energy directly to the reagents which can enhanced heat transfer efficiency. Based on the advantages of using microwave-assisted process, this study aims to optimize biodiesel production from E. coli cell membrane using microwave-assisted heating. Experimental results showed that the microwave radiation exhibited a notable enhanced effect for transesterification by using the microwave radiation compared with that of the conventional heating method. A maximum yield of 4.19% was obtained using 80:1 mass ratio of methanol to biomass, 0.3:1 mass ratio of H2SO4 to biomass, at 110℃ under microwave radiation after 30 min. From the experimental result, the reaction can be completed in much shorter time by using microwave-assisted heating, consequently reducing energy consumption, byproduct formation and solvent usage.
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