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Author Lohmeier-Vogel, Elke ♦ Cao, Rong ♦ Roos, Stefan ♦ Niel, W. J. Van
Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Phosphoketolase Pathway Dominates ♦ Containing Dual Pathway ♦ Glycolytic Pathway ♦ Biomass Yield ♦ Glucose-metabolizing Cell ♦ Simultaneous Operation ♦ Growth Performance ♦ External Electron Acceptor ♦ Central Carbon Metabolic Pathway ♦ Three-carbon Intermediate Stage ♦ Observed Behavior ♦ Lactic Acid Bacteria ♦ Energy Starvation ♦ Maximum Specific Growth Rate ♦ Phosphorylated Emp ♦ Atp Production Flux ♦ Exponential Growth Phase ♦ Enzyme Activity ♦ Phosphoglucoi-somerase Activity ♦ Redox Imbalance ♦ Sucrose-metabolizing Cell ♦ Embden-meyerhof Pathway ♦ Low Atp Level ♦ Main Flux ♦ Twofold Increase ♦ 6-bisphosphate Aldolase ♦ Metabolic Flux Analysis ♦ Heterofermentative Lactobacillus Reuteri Strain Atcc
Abstract Metabolic flux analysis indicated that the heterofermentative Lactobacillus reuteri strain ATCC 55730 uses both the Embden-Meyerhof pathway (EMP) and phosphoketolase pathway (PKP) when glucose or sucrose is converted into the three-carbon intermediate stage of glycolysis. In all cases studied, the main flux is through the PKP, while the EMP is used as a shunt. In the exponential growth phase, 70%, 73%, and 84 % of the flux goes through the PKP in cells metabolizing (i) glucose plus fructose, (ii) glucose alone, and (iii) sucrose alone, respectively. Analysis of the genome of L. reuteri ATCC 55730 confirmed the presence of the genes for both pathways. Further evidence for the simultaneous operation of two central carbon metabolic pathways was found through the detection of fructose-1,6-bisphosphate aldolase, phosphofructokinase, and phosphoglucoi-somerase activities and the presence of phosphorylated EMP and PKP intermediates using in vitro 31P NMR. The maximum specific growth rate and biomass yield obtained on glucose were twice as low as on sucrose. This was the result of low ATP levels being present in glucose-metabolizing cells, although the ATP production flux was as high as in sucrose-metabolizing cells due to a twofold increase of enzyme activities in both glycolytic pathways. Growth performance on glucose could be improved by adding fructose as an external electron acceptor, suggesting that the observed behavior is due to a redox imbalance causing energy starvation. Lactic acid bacteria (LAB) employ a few glycolytic pathways
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Publisher Date 2007-01-01