| Summary: | 博士 === 國立中央大學 === 化學工程與材料工程研究所 === 97 === This research study consists of two major parts. The first part studies the effect of light on the submerged culture of Aspergillus ficcum, and the second part investigates the role of Microbacterium sp. in the removal of dimethyl sulfide.
The first part studies on the effect of light on the submerged culture of Aspergillus ficuum confirm that Bacillus subtilis is equipped with photoreceptor protein genes that react to light sources. Prior research conducted by this laboratory verifies that the intensity of white light affects the activity of Nattokinase, while light intensity and wavelength affects the phytase activity of Aspergillus ficuum. By observing that light wavelength influences growth and physiological activity in various ways, this thesis addresses the relevance of light intensity and wavelength on the physiological cycle and metabolite of Aspergillus ficuum and examines light-induced behavior in thees production of metabolites with LC analysis. Results indicate that Aspergillus ficuum possess a response and regulatory system that adapts to different light sources.
The second part of this thesis investigates the role of Microbacterium sp. in the removal of dimethyl sulfide. The removal of dimethyl sulfide (DMS) from industrial gas streams has received a high priority due to its very low odorous threshold value and relatively low biodegradability compared to other reduced sulfur compounds. A variety of bacteria that utilize DMS as a carbon/energy source have been studied and the degradation pathway elucidated. However, to date, there have been few reports on the industrial application of such bacteria inoculated into a bioreactor for DMS treatment. An additional problem of such systems is the accumulation of intermediate metabolites that strongly impact on DMS removal by the microbe. The results reported here were obtained using a bioreactor inoculated with the H2S-degrader Pseudomonas putida and the DMS-degrader Microbacterium sp. NTUT26 to facilitate removal of metabolic intermediates and DMS. This bioreactor performed well (1.71 g-S/day/ kg-dry packing material) in terms of DMS gas removal, based on an evaluation of the apparent kinetics and maximal removal capacity of the system. Under varying conditions (changes in start-up, inlet loading, shutdown, and re-start), the bioreactor inoculated with Microbacterium sp. NTUT26 and Pseudomonas putida enhanced removal of high concentrations of DMS. Our results suggest that this type of bioreactor system has significant potential applications in treating (industrial) DMS gas streams.
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