Overexpression of glucose-6-phosphate dehydrogenase enhances riboflavin production in Bacillus subtilis |
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Authors: | Yun Xia Duan Tao Chen Xun Chen Xue Ming Zhao |
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Institution: | (1) Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin, 300072, China;(2) Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, 300072, China;(3) Present address: Tianjin Academy of Environmental Sciences, Fukang Road, Tianjin, 300191, China; |
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Abstract: | Carbon flow in Bacillus subtilis through the pentose phosphate (PP) pathway was modulated by overexpression of glucose-6-phosphate dehydrogenase (G6PDH) under
the control of the inducible Pxyl promoter in B. subtilis PY. Alteration of carbon flow into the PP pathway will affect the availability of ribulose-5-phosphate (Ru5P) and the riboflavin
yield. Overexpression of G6PDH resulted in the glucose consumption rate increasing slightly, while the specific growth rate
was unchanged. An improvement by 25% ± 2 of the riboflavin production was obtained. Compared to by-products formation in flask
culture, low acid production (acetate and pyruvate) and more acetoin were observed. Metabolic analysis, together with carbon
flux redistribution, indicated that the PP pathway fluxes are increased in response to overexpression of G6PDH. Moreover,
increased flux of the PP pathway is associated with an increased intracellular pool of Ru5P, which is a precursor for riboflavin
biosynthesis. The high concentrations of Ru5P could explain the increased riboflavin production. |
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