| Summary: | 博士 === 國立清華大學 === 化學工程學系 === 90 === The objectives of this research are to gain more science and engineering insights regarding the development and application of cell immobilization and fermentation technique. Three kinds of material, polyvinyl alcohol (PVA), polyacrylamide (PAA) and anionic polyurethane (APU) will be investigated in this thesis. In addition, a system for the production of clavulanic acid, a -lactamase inhibitor, was established which is expected to be used in immobilization process.
A single stage PVA immobilized-cell reactor with three operation modes, i.e. continuous aeration, intermittent aeration (IA), and IA with real-time control using oxidation-reduction-potential (ORP), was used to investigate the efficiency of simultaneous removal of carbon and nitrogen from raw swine wastewater. The results revealed that the chemical oxygen demand (COD) removal efficiency and total-nitrogen (T-N) removal efficiency in the IA mode were higher than that in the continuous aeration mode. When the ORP control was adopted in the IA mode, the total cycle time could be reduced by about 20%.
Immobilized growing cells of Candida tropicalis were prepared by entrapment into polyacrylamide (PAA) gel beads. The formation of PAA gel beads was accomplished in aqueous phase associated with the gelling reaction of Ca-alginate. Effects of monomer concentration and crosslinker content on the diffusivity of phenol in gel beads were studied. The immobilized-cell beads were used to degrade phenol in an air-lift bioreactor undergoing continuous operation. A stable removal efficiency of more than 95 % was achieved even at an inlet phenol concentration as high as 5000 mg l-1. And, the maximum biodegradation rate of 7.68 g l-1 d-1 was reached.
A new cell immobilization method based on the gelation of anionic polyurethane (APU) has been developed. APU is non-toxic against living yeast cells and the preparation of gel-entrapped cells can easily be achieved under very mild conditions. The formed gel beads then posses high mechanical strength. The immobilization method was illustrated by an ethanol production process using bakers’ yeast (Saccharomyces cerevisiae). The results imply that the cells entrapped by this method are useful for a variety of purposes
The addition of glycerol, ornithine and arginine had significant effects on the biosynthesis of clavulanic acid in Streptomyces. clavuligerus. Glycerol at initial concentration of 10-20 g l-1 increases clavulanic acid production by Streptomyces clavuligerus in flask culture. Adding ornithine in batch culture could enhance clavulanic acid production but arginine showed little effect. In the fed-batch experiments, the results showed that glycerol (C3) supply rather than amino acid (C5) supply is rate-limiting. Feeding ornithine not only provided an enough supply of arginine for clavulanic acid production, but also inhibited the glycerol-utilizing cephamycin biosynthesis. The results reveal that ornithine rather than arginine could enhance effectively clavulanic acid production if the amount of C3-precursor was sufficient.
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