Metabolic flux analysis using stoichiometric models for Aspergillus niger: Comparison under glucoamylase-producing and non-producing conditions

Melzer, Guido; Dalpiaz, A.; Grote, Andreas; Kucklick, Martin; Göcke, Yvonne; Jonas, Rochus; Dersch, Petra; Franco‐Lara, Ezequiel; Nörtemann, Bernd; Hempel, D. C.

doi:10.1016/j.jbiotec.2007.08.034

Cited by 19 publications

(17 citation statements)

References 38 publications

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“…As a powerful tool for evaluating metabolic distribution within cells, intracellular flux analysis has been applied to many microbial cultures for the purpose of improvement of production processes (Vallino and Stephanopoulos 1993;Shi et al 1997;Melzer et al 2007;Iwatani et al 2008). Knowledge of intracellular flux distributions under different conditions makes it possible to understand the fundamental metabolism in detail and gives useful information which can be applied to bioreactor design and control strategies of culture systems.…”

Section: Introductionmentioning

confidence: 99%

Carbon metabolism and energy conversion of Synechococcus sp. PCC 7942 under mixotrophic conditions: comparison with photoautotrophic condition

et al. 2011

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To investigate the carbon metabolism and energy conversion efficiency of the cyanobacterium Synechococcus sp. PCC 7942 under mixotrophic conditions, we studied its growth characteristics in mixotrophic cultures with glucose and with acetate, respectively, and further discussed the carbon metabolism and energy utilization based on metabolic flux analysis. Results showed that both glucose and acetate could enhance the growth of Synechococcus sp. PCC 7942. The metabolic flux through the glycolytic pathway, tricarboxylic acid cycle, and mitochondrial oxidative phosphorylation was affected by the two organic substrates. Additionally, the cellular composition was also modulated by glucose and acetate. Under mixotrophic conditions, glucose exerts more significant impact on the diminishment of photochemical efficiency. Although the contribution of light energy was smaller, the cell yields based on total energy in mixotrophic cultures were higher compared with that of photoautotrophic one. On the basis of chlorophyll fluorescence analysis, the actual energy conversion efficiencies based on ATP synthesis in the photoautotrophic, glucose-mixotrophic, and acetatemixotrophic cultures were evaluated to be 4.59%, 5.86%, and 6.60%, respectively. Keywords Synechococcus sp. PCC 7942 . Mixotrophic cultivation . Carbon metabolism . Energy conversion . Metabolic flux analysis . Chlorophyll fluorescence analysis Nomenclature a ij Stoichiometric coefficient of metabolite i in the jth reaction (−) A m×nMatrix of stoichiometric coefficient (−) A 0 Side area of flask receiving incident light (m 2 ) E abLight energy absorbed by the biomass unit (kJ g −1 h −1 ) E P Actual light energy for photosynthesis (kJ g −1 h −1 ) E C Chemical energy received from organic carbon resources (kJ g −1 h −1 ) E C,ACE Chemical energy originated from acetate (kJ g −1 h −1 ) E C,GLC Chemical energy originated from glucoseThe total absorbed energy (kJ g −1 h −1 ) I 0 Incident light intensity (μmol m− 2 s −1 ) K a Effective absorption coefficient of light (m −1 ) rVector of m-dimensional metabolite accumulation rate (mmol g −1 h −1 ) r ATP Relative rate of ATP synthesized (mmol g −1 h −1 ) r ACE Relative rate of acetate consumption (mmol g −1 h −1 ) r ex Subvector of extracellular metabolite accumulation rate (mmol g −1 h −1 )Relative rate of glucose consumption (mmol g −1 h −1 ) r i Accumulation rate of metabolite i (mmol g −1 h −1 ) r in Subvector of intracellular metabolite accumulation rate (mmol gof cell mass based on ATP generation (g mol-ATP −1 ) Y E Cell yield based on total light energy (g kJ −1 ) ΔG o ACE Free energy change of acetate complete oxidation (kJ mol −1 ) ΔG o ATP Free energy change of ATP hydrolysis (kJ mol −1 ) ΔG o GLC Free energy change of glucose complete oxidation (kJ mol −1 ) μ Specific growth rate (h −1 ) 8 Vector of measurement noise variancecovariance (−) Φ PSII The efficiency of photosystem II photochemistry (−) Ψ ATP The efficiency of energy conversion on ATP synthesis (%)

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Section: Introductionmentioning

confidence: 99%

Carbon metabolism and energy conversion of Synechococcus sp. PCC 7942 under mixotrophic conditions: comparison with photoautotrophic condition

et al. 2011

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“…During non-producing conditions on D-xylose changing pH values of the cultivation medium had no influence on the fluxes of the central carbon metabolism. D-Glucose as carbon source (producing conditions) caused a significant increase in PPP activity and an increased NADPH supply for protein biosynthesis [23]. Applying 13 C gluconate as tracer the activity of the PPP of Penicillin-G producing and non-producing chemostat cultures of Penicillium chrysogenum was determined, pointing to a strong correlation of PPP activity and b-lactame production to meet the cytosolic demand for NADPH [24].…”

Section: Metabolic Flux Analysis In Fungimentioning

confidence: 98%

Metabolic flux analysis in eukaryotes

Niklas

Schneider

Heinzle

2010

Current Opinion in Biotechnology

114

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“…Typically, carbon fluxes into and out of the cell are estimated by measuring extracellular concentrations and biomass and used to calculate the fluxes in the cell. Stoichiometric models for the central metabolism and full genome-scale of A. niger (David et al (2003), Melzer et al (2007), Andersen et al (2008a)) and a genome scale model for A. nidulans (David et al, 2006) have been published previously, and a genome-scale model for A. oryzae is currently in review (Vongsangnak et al, personal communications).…”

Section: Modelingmentioning

confidence: 99%

“…When testing all combinations of two gene deletions, it was found that a fruitful strategy might be a deletion of ATP:citrate oxaloacetate-lyase and pyruvate decarboxylase giving a yield of at least 1.12 mol succinate per mol glucose. A smaller model of A. niger metabolism has been presented by Melzer et al (2007) based on the model of David et al (2003) and other information, and this model was used to predict metabolic fluxes through pathways of central metabolism in cultivations on two different media and at varying levels of ambient pH.…”

Section: Stoichiometric Modelingmentioning

confidence: 99%