Fed-batch fermentation of recombinant Citrobacter freundii with expression of a violacein-synthesizing gene cluster for efficient violacein production from glycerol |
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| Institution: | 1. Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China;2. Institute of Microbiology, Xinjiang Academy of Agricultural Science, Urumqi 830000, China;1. Department of Radiation Oncology, Karadeniz Technical University, Trabzon, Turkey;2. Department of Radiation Oncology, Akdeniz University, Antalya, Turkey;3. Department of Radiation Oncology, Kanuni Research and Education Hospital, Trabzon, Turkey;1. State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China;2. Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040, China;1. Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China;2. Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China;3. University of Science and Technology of China, Hefei 230026, PR China;4. University of Chinese Academy of Sciences, Beijing 100049, PR China;5. College of Materials and Energy, South China Agricultural University, Guangzhou 510642, PR China;1. College of Energy, Xiamen University, Xiamen 361005, PR China;2. Xiamen Key Laboratory of High-valued Conversion Technology of Agricultural Biomass, Xiamen University, Xiamen, PR China;3. Fujian Vocational College of Bioengineering, Fuzhou, PR China;1. Beijing Key Lab of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China;2. Amoy-BUCT Industrial of Bio-technovation Institute, Amoy, 361022, China |
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| Abstract: | The extensive prospects of violacein in the pharmaceutical industry have attracted increasing interest. However, the fermentation levels of violacein are currently inadequate to meet the demands of industrial production. This study was undertaken to develop an efficient process for the production of violacein by recombinant Citrobacter freundii. The effects of dissolved oxygen (DO) and pH on cell growth and violacein production in batch cultures were investigated first. When the DO and pH of the medium were controlled at around 25% and 7.0, respectively, the biomass and concentration of violacein were maximized. Based on the consumption of nutrients in the medium observed during batch culture, a fed-batch fermentation strategy with controlled DO and pH was implemented. By continuously feeding glycerol, NH4Cl, and l-tryptophan at a constant feeding rate of 16 mL h?1, the final concentration of violacein reached 4.13 g L?1, which was 4.09-fold higher than the corresponding batch culture, and the maximal dry cell weight (DCW) and average violacein productivity obtained for the fed-batch culture were 3.34 g DCW L?1 and 82.6 mg L?1 h?1, respectively. To date, this is the first report on the efficient production of violacein by genetically engineered strains in a fermentor. |
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