Acetic acid formation in <i>escherichia coli</i> fermentation

Han, Keehyun; Lim, Henry C.; Hong, Juan

doi:10.1002/bit.260390611

Cited by 180 publications

(122 citation statements)

References 15 publications

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“…Acetate production and secretion is an overflow mechanism generally interpreted as resulting from an imbalance between carbon uptake/availability and the metabolic network capacity to use it for energy and biomass production 24 . On the other hand, it is also an important source of energy generation through substrate-level phosphorylation 25 . In addition to acetate secretion, we found that both GLPK and DKI strains also secrete significant levels of D-lactate (Fig.…”

Section: Resultsmentioning

confidence: 99%

Global metabolic network reorganization by adaptive mutations allows fast growth of Escherichia coli on glycerol

et al. 2014

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Comparative whole-genome sequencing enables the identification of specific mutations during adaptation of bacteria to new environments and allelic replacement can establish their causality. However, the mechanisms of action are hard to decipher and little has been achieved for epistatic mutations, especially at the metabolic level. Here we show that a strain of Escherichia coli carrying mutations in the rpoC and glpK genes, derived from adaptation in glycerol, uses two distinct metabolic strategies to gain growth advantage. A 27-bp deletion in the rpoC gene first increases metabolic efficiency. Then, a point mutation in the glpK gene promotes growth by improving glycerol utilization but results in increased carbon wasting as overflow metabolism. In a strain carrying both mutations, these contrasting carbon/energy saving and wasting mechanisms work together to give an 89% increase in growth rate. This study provides insight into metabolic reprogramming during adaptive laboratory evolution for fast cellular growth.

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Section: Resultsmentioning

confidence: 99%

Global metabolic network reorganization by adaptive mutations allows fast growth of Escherichia coli on glycerol

et al. 2014

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“…All attribute acetate formation either to limitations in respiratory NADH turnover and concomitant ATP generation through oxidative phosphorylation (Andersen & von Meyenburg, 1980;Doelle et al, 1982;Reiling et al, 1985;Varma & Palsson, 1994) or to initial limitations in the TCA cycle (Majewski & Domach, 1990;Han et al, 1992). Moreover, Han et al (1992) concluded that these limitations cause a reorganization of the catabolic flux distribution to meet the anabolic demands at high growth rates by generating the necessary amount of energy by using both oxidative metabolism and acetic acid formation.…”

Section: Discussionmentioning

confidence: 99%

Metabolic flux analysis of Escherichia coli in glucose-limited continuous culture. I. Growth-rate-dependent metabolic efficiency at steady state

Kayser¹,

Weber²,

Hecht³

et al. 2005

Microbiology

167

170

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The Escherichia coli K-12 strain TG1 was grown at 28 6C in aerobic glucose-limited continuous cultures at dilution rates ranging from 0?044 to 0?415 h "1 . The rates of biomass formation, the specific rates of glucose, ammonium and oxygen uptake and the specific carbon dioxide evolution rate increased linearly with the dilution rate up to 0?3 h "1 . At dilution rates between 0?3 h "1 and 0?4 h "1 , a strong deviation from the linear increase to lower specific oxygen uptake and carbon dioxide evolution rates occurred. The biomass formation rate and the specific glucose and ammonium uptake rates did not deviate that strongly from the linear increase up to dilution rates of 0?4 h "1 . An increasing percentage of glucose carbon flow towards biomass determined by a reactor mass balance and a decreasing specific ATP production rate concomitant with a decreasing adenylate energy charge indicated higher energetic efficiency of carbon substrate utilization at higher dilution rates. Estimation of metabolic fluxes by a stoichiometric model revealed an increasing activity of the pentose phosphate pathway and a decreasing tricarboxylic acid cycle activity with increasing dilution rates, indicative of the increased NADPH and precursor demand for anabolic purposes at the expense of ATP formation through catabolic activities. Thus, increasing growth rates first result in a more energy-efficient use of the carbon substrate for biomass production, i.e. a lower portion of the carbon substrate is channelled into the respiratory, energy-generating pathway. At dilution rates above 0?4 h "1 , close to the wash-out point, respiration rates dropped sharply and accumulation of glucose and acetic acid was observed. Energy generation through acetate formation yields less ATP compared with complete oxidation of the sugar carbon substrate, but is the result of maximized energy generation under conditions of restrictions in the tricarboxylic acid cycle or in respiratory NADH turnover. Thus, the data strongly support the conclusion that, in aerobic glucose-limited continuous cultures of E. coli TG1, two different carbon limitations occur: at low dilution rates, cell growth is limited by cell-carbon supply and, at high dilution rates, by energy-carbon supply.

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“…It is well known that during rapid aerobic growth, E. coli produces acetate as a by-product. The metabolism of E. coli switches from respiration to fermentation when cells grow at a high specific growth rate with a low glucose concentration even under aerobic conditions (3,10). It has been suggested that an increase in cell growth rate presumably increases glucose uptake rate and intracellular glucose concentration (23).…”

Section: Discussionmentioning

confidence: 99%

Oxygen- and Growth Rate-Dependent Regulation of Escherichia coli Fumarase (FumA, FumB, and FumC) Activity

Tseng

Lin

et al. 2001

J Bacteriol

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Escherichia coli contains three biochemically distinct fumarases which catalyze the interconversion of fumarate to L-malate in the tricarboxylic acid cycle. Batch culture studies indicated that fumarase activities varied according to carbon substrate and cell doubling time. Growth rate control of fumarase activities in the wild type and mutants was demonstrated in continuous culture; FumA and FumC activities were induced fourto fivefold when the cell growth rate (k) was lowered from 1.2/h to 0.24/h at 1 and 21% O 2 , respectively. There was a twofold induction of FumA and FumC activities when acetate was utilized instead of glucose as the sole carbon source. However, these fumarase activities were still shown to be under growth rate control. Thus, the activity of the fumarases is regulated by the cell growth rate and carbon source utilization independently. Further examination of FumA and FumC activities in a cya mutant suggested that growth rate control of FumA and FumC activities is cyclic AMP dependent. Although the total fumarase activity increased under aerobic conditions, the individual fumarase activities varied under different oxygen levels. While FumB activity was maximal during anaerobic growth (k ‫؍‬ 0.6/h), FumA was the major enzyme under anaerobic cell growth, and the maximum activity was achieved when oxygen was elevated to 1 to 2%. Further increase in the oxygen level caused inactivation of FumA and FumB activities by the high oxidized state, but FumC activity increased simultaneously when the oxygen level was higher than 4%. The same regulation of the activities of fumarases in response to different oxygen levels was also found in mutants. Therefore, synthesis of the three fumarase enzymes is controlled in a hierarchical fashion depending on the environmental oxygen that the cell encounters.

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Acetic acid formation in escherichia coli fermentation

Cited by 180 publications

References 15 publications

Global metabolic network reorganization by adaptive mutations allows fast growth of Escherichia coli on glycerol

Global metabolic network reorganization by adaptive mutations allows fast growth of Escherichia coli on glycerol

Metabolic flux analysis of Escherichia coli in glucose-limited continuous culture. I. Growth-rate-dependent metabolic efficiency at steady state

Oxygen- and Growth Rate-Dependent Regulation of Escherichia coli Fumarase (FumA, FumB, and FumC) Activity

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