Overexpression of glucose-6-phosphate dehydrogenase enhances riboflavin production in Bacillus subtilis.
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% + or - 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.
Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Tianjin 300072, China.
Yun Xia
YX
Duan
Tao
T
Chen
Xun
X
Chen
Xue Ming
XM
Zhao
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics; D010427:Pentose Phosphate Pathway; D011773:Pyruvates / Q000378:metabolism; D012256:Riboflavin / Q000096:biosynthesis* / Q000235:genetics; D012274:Ribulosephosphates / Q000378:metabolism
D001426:Bacterial Proteins; D011773:Pyruvates; D012274:Ribulosephosphates; C031524:ribulose 5-phosphate; D005954:Glucosephosphate Dehydrogenase; D005947:Glucose; D012256:Riboflavin