Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 371599
Title Increased NADPH concentration obtained by metabolic engineering of the pentose phosphate pathway in Aspergillus niger
Author(s) Poulsen, B.R.; Nohr, J.; Douthwaite, S.; Hansen, L.V.; Iversen, J.J.L.; Visser, J.; Ruijter, G.J.G.
Source FEBS Journal 272 (2005)6. - ISSN 1742-464X - p. 1313 - 1325.
Department(s) AFSG Staff Departments (WUATV)
WU Agrotechnology and Food SciencesDepartment of Agrotechnology and Food Sciences
Publication type Refereed Article in a scientific journal
Publication year 2005
Keyword(s) saccharomyces-cerevisiae - phosphoglucose isomerase - penicillium-chrysogenum - ralstonia-eutropha - filamentous fungi - escherichia-coli - acid production - genes - flux - overexpression
Abstract Many biosynthetic reactions and bioconversions are limited by low availability of NADPH. With the purpose of increasing the NADPH concentration and/or the flux through the pentose phosphate pathway in Aspergillus niger, the genes encoding glucose 6-phosphate dehydrogenase (gsdA), 6-phosphogluconate dehydrogenase (gndA) and transketolase (tktA) were cloned and overexpressed in separate strains. Intracellular NADPH concentration was increased two- to ninefold as a result of 13-fold overproduction of 6-phosphogluconate dehydrogenase. Although overproduction of glucose 6-phosphate dehydrogenase and transketolase changed the concentration of several metabolites it did not result in increased NADPH concentration. To establish the effects of overexpression of the three genes, wild-type and overexpressing strains were characterized in detail in exponential and stationary phase of bioreactor cultures containing minimal media, with glucose as the carbon source and ammonium or nitrate as the nitrogen source and final cell density limiting substrate. Enzymes, intermediary metabolites, polyol pools (intra- and extracellular), organic acids, growth rates and rate constant of induction of acid production in postexponential phase were measured. None of the modified strains had a changed growth rate. Partial least square regressions showed the correlations between NADPH and up to 40 other variables (concentration of enzymes and metabolites) and it was possible to predict the intracellular NADPH concentration from relatively easily obtainable data (the concentration of enzymes, polyols and oxalate). This prediction might be used in screening for high NADPH levels in engineered strains or mutants of other organisms.
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