Genetic engineering of Ketogulonigenium vulgare for enhanced production of 2-keto-L-gulonic acid |
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Authors: | Cai Lei Yuan Mei-Qing Li Zheng-Jun Chen Jin-Chun Chen Guo-Qiang |
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Affiliation: | a Dept Biological Sciences and Biotechnology, MOE Key Lab. Bioinformatics (& System Biology), Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China b Institute of Forensic Sciences, Ministry of Public Security, Beijing 100038, China c College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China |
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Abstract: | Folate derivatives are crucial growth factors for Ketogulonigenium vulgare which is used in mixed culture with Bacillus megaterium for the industrial production of 2-keto-l-gulonic acid (2-KGA), the precursor of l-ascorbic acid (l-AA) or vitamin C (Vc). To improve the growth and 2-KGA production, five genes involved in folate biosynthesis identified in a folate gene cluster from Lactococcus lactis MG1363, including folB, folKE, folP, folQ and folC, were over-expressed in K. vulgare. Intracellular folate concentration in the recombinant strain harboring folate biosynthesis genes cluster under the control of Psdh (sorbose dehydrogenase gene sdh promoter from K. vulgare) was 8 times higher than that of the wildtype K. vulgare DSM 4025 (P < 0.001). In shake flask studies, the cell density and 2-KGA production of the recombinant K. vulgare Rif (pMCS2PsdhfolBC) were increased by 18% (P < 0.001) and 14% (P < 0.001), respectively, under a relatively stable pH 7 condition. In fermentor studies, enhancements around 25% cell density (P < 0.001) and approximately 35% 2-KGA productivity (P < 0.001) were observed in comparison with the controls without over-expressing the folate biosynthesis genes. This was the first successful study of metabolic engineering on K. vulgare for enhanced 2-KGA production. |
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Keywords: | Ketogulonigenium vulgare 2-Keto- smallcaps" >l-gulonic acid Folate Vitamin C Synthetic biology |
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