| Summary: | 碩士 === 大同大學 === 生物工程研究所 === 89 === Haolferax mediterranei can produce polyhydroxybutyrate (PHB) in a hyper-saline condition, therefore it did not contamination problem during continuous culture. In this studies, we used glucose and yeast extract as carbon and nitrogen source for the production of PHB under the pH-stat fed-batch control strategy. The best feeding ratio of glucose/YE was found as 1/1.7 g/g；after 117 hours culture, the cell dry weight, PHB concentration and PHB content were 85.8 g/L, 23.2 g/L and 27%(w/w) respectively；the maximum cell growth rate was 1.14 g/L·hr. during culture the concentration of salt was maintained by maintaining the conductivity of fermentation broth.
By using 1/1.7 g/g of extruded starch/YE to replace glucose/YE in the pH-stat fed-batch culture, after 69 hours, the cell dry weight, PHB concentration and PHB content were 32 g/L, 12.0 g/L and 31%(w/w) respectively；the maximum cell growth rate was 1.19 g/L·hr；the maximum cell concentration of 50.6 g/L can be reached after 85 hrs culture. By using repeated fed-batch culture and 1/1.7 g/g extruded starch/YE as carbon/nitrogen source, after 123 hrs, the cell dry weight, PHB concentration and PHB content were reached 70.3 g/L, 20 g/L and 29%(w/w) respectively. In this studies, we proved that high PHB concentration can be produced continuously during hyper-saline condition. Besides, we found that nitrogen restriction had no influence on the production of PHB by Haolferax mediterranei.
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