Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model

Idiophase, the citric acid producing stage of Aspergillus niger was mathematically modeled to identify required genetic manipulations to optimize citric acid production rate. For this reason, a consistent picture of cell functioning had to be achieved. The transient idiophase nature was established...

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Autores principales:	Guebel,Daniel V., Torres Darias,Néstor V.
Lenguaje:	English
Publicado:	Pontificia Universidad Católica de Valparaíso 2001
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100001
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spelling	oai:scielo:S0717-345820010001000012005-12-12Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance modelGuebel,Daniel V.Torres Darias,Néstor V. Idiophase, the citric acid producing stage of Aspergillus niger was mathematically modeled to identify required genetic manipulations to optimize citric acid production rate. For this reason, a consistent picture of cell functioning had to be achieved. The transient idiophase nature was established by stoichiometric analysis. The main intracellular fluxes were computed by application of material and physiological constraints (ATP, reduction equivalents, proton motive force) at culture time 120 hours. The HMP pathway accounts for 16% of the glucose input (carbon basis), the Krebs cycle for 13% and the citric acid synthesis for the remaining 71%. This profile implies an operative glycerol-P shuttle. It recycles 93% of the cytosolic glycerol-P to cytosolic DHAP thus coupling the transformation of cytosolic NADH to mitochondrial FADH. A cellular maintenance energy of 3.7 mmol ATP/g·h was determined. It would be spent in fueling cytoplasmatic (1.4 mmol H+/g·h) and mitochondrial (1.8 mmol H+/g·h) H+-ATPase pumps with efficiencies of 0.65 and 1.2 mmol H+/mmol ATP respectively. The role and extent of the alternative respiration system activity and polyol excretion is accounted by the model as well. In addition, the significance of GABA shunt and futile NH4+/NH3 cycle were rejected. According to the developed model, the specific citric productivity would be increased in 45% by an unique change if glucose influx were duplicated. Differences with predictions from other model that required many manipulations are also discussed.info:eu-repo/semantics/openAccessPontificia Universidad Católica de ValparaísoElectronic Journal of Biotechnology v.4 n.1 20012001-04-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100001en
institution	Scielo Chile
collection	Scielo Chile
language	English
description	Idiophase, the citric acid producing stage of Aspergillus niger was mathematically modeled to identify required genetic manipulations to optimize citric acid production rate. For this reason, a consistent picture of cell functioning had to be achieved. The transient idiophase nature was established by stoichiometric analysis. The main intracellular fluxes were computed by application of material and physiological constraints (ATP, reduction equivalents, proton motive force) at culture time 120 hours. The HMP pathway accounts for 16% of the glucose input (carbon basis), the Krebs cycle for 13% and the citric acid synthesis for the remaining 71%. This profile implies an operative glycerol-P shuttle. It recycles 93% of the cytosolic glycerol-P to cytosolic DHAP thus coupling the transformation of cytosolic NADH to mitochondrial FADH. A cellular maintenance energy of 3.7 mmol ATP/g·h was determined. It would be spent in fueling cytoplasmatic (1.4 mmol H+/g·h) and mitochondrial (1.8 mmol H+/g·h) H+-ATPase pumps with efficiencies of 0.65 and 1.2 mmol H+/mmol ATP respectively. The role and extent of the alternative respiration system activity and polyol excretion is accounted by the model as well. In addition, the significance of GABA shunt and futile NH4+/NH3 cycle were rejected. According to the developed model, the specific citric productivity would be increased in 45% by an unique change if glucose influx were duplicated. Differences with predictions from other model that required many manipulations are also discussed.
author	Guebel,Daniel V. Torres Darias,Néstor V.
spellingShingle	Guebel,Daniel V. Torres Darias,Néstor V. Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
author_facet	Guebel,Daniel V. Torres Darias,Néstor V.
author_sort	Guebel,Daniel V.
title	Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
title_short	Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
title_full	Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
title_fullStr	Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
title_full_unstemmed	Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model
title_sort	optimization of the citric acid production by aspergillus niger through a metabolic flux balance model
publisher	Pontificia Universidad Católica de Valparaíso
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582001000100001
work_keys_str_mv	AT guebeldanielv optimizationofthecitricacidproductionbyaspergillusnigerthroughametabolicfluxbalancemodel AT torresdariasnestorv optimizationofthecitricacidproductionbyaspergillusnigerthroughametabolicfluxbalancemodel
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Optimization of the citric acid production by Aspergillus niger through a metabolic flux balance model

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