Maintenance metabolism and carbon fluxes in Bacillus species

Tännler, Simon; Decasper, Seraina; Sauer, Uwe

doi:10.1186/1475-2859-7-19

Cited by 68 publications

(70 citation statements)

References 38 publications

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“…Although batch cultures are not ideally suited for accurate carbon flux determinations, our data do seem to be in line with reported values for wild-type B. subtilis (32). With the assumptions made previously regarding O 2 utilization, our data (see Table S3 in the supplemental material) for WOA-stressed cells show reasonably close C balances for all stresses, apart from 25 mM K-Ac, with which cells appeared to use about 3.5 times as much O 2 as the amount estimated on the basis of carbon fluxes based solely on glycolysis and fermentation.…”

Section: Resultssupporting

confidence: 78%

Distinct Effects of Sorbic Acid and Acetic Acid on the Electrophysiology and Metabolism of Bacillus subtilis

Beilen

Mattos

Hellingwerf

et al. 2014

Appl Environ Microbiol

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b Sorbic acid and acetic acid are among the weak organic acid preservatives most commonly used to improve the microbiological stability of foods. They have similar pK a values, but sorbic acid is a far more potent preservative. Weak organic acids are most effective at low pH. Under these circumstances, they are assumed to diffuse across the membrane as neutral undissociated acids. We show here that the level of initial intracellular acidification depends on the concentration of undissociated acid and less on the nature of the acid. Recovery of the internal pH depends on the presence of an energy source, but acidification of the cytosol causes a decrease in glucose flux. Furthermore, sorbic acid is a more potent uncoupler of the membrane potential than acetic acid. Together these effects may also slow the rate of ATP synthesis significantly and may thus (partially) explain sorbic acid's effectiveness.

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Section: Resultssupporting

confidence: 78%

Distinct Effects of Sorbic Acid and Acetic Acid on the Electrophysiology and Metabolism of Bacillus subtilis

Beilen

Mattos

Hellingwerf

et al. 2014

Appl Environ Microbiol

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“…The here-predicted reversibilities are generally in agreement with previously made modeling assumptions (16,22,36). Nevertheless, roughly two-thirds of the investigated reversibilities remain undefined.…”

Section: Intracellular Metabolite Concentrations and Reactionsupporting

confidence: 77%

“…6A) compares favorably to previously reported values for the same strain (22,37). Glucose was primarily catabolized through glycolysis and then either secreted as acetate or combusted to CO 2 via the TCA cycle.…”

Section: Intracellular Metabolite Concentrations and Reactionsupporting

confidence: 76%

“…From balancing the NADPH-consuming and -producing fluxes (Fig. 7), it is obvious that the catabolic NADPH production via the PP pathway and isocitrate dehydrogenase match the anabolic demands during growth on glucose as described before (22). In the presence of malate, however, these two sources of NADPH are insufficient such that about 40 -50% of the anabolic NADPH demand must be supplied via the NADPH-dependent malic enzyme (Fig.…”

Section: Intracellular Metabolite Concentrations and Reactionmentioning

confidence: 99%

“…Specific rates were calculated by regression analysis for at least five time points during the exponential growth phase as described previously (21). Cell growth was monitored photometrically at 600 nm, and cell dry weight was inferred from a predetermined conversion factor of 0.48 g of cells/A 600 (22). All physiological parameters were determined during the exponential growth phase, typically ranging from 0.10 to 1.5 A 600 .…”

Section: Methodsmentioning

confidence: 99%

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Metabolic Fluxes during Strong Carbon Catabolite Repression by Malate in Bacillus subtilis

Kleijn

Buescher²,

Chat³

et al. 2010

Journal of Biological Chemistry

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103

110

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Commonly glucose is considered to be the only preferred substrate in Bacillus subtilis whose presence represses utilization of other alternative substrates. Because recent data indicate that malate might be an exception, we quantify here the carbon source utilization hierarchy. Based on physiology and transcriptional data during co-utilization experiments with eight carbon substrates, we demonstrate that malate is a second preferred carbon source for B. subtilis, which is rapidly co-utilized with glucose and strongly represses the uptake of alternative substrates. From the different hierarchy and degree of catabolite repression exerted by glucose and malate, we conclude that both substrates might act through different molecular mechanisms. To obtain a quantitative and functional network view of how malate is (co)metabolized, we developed a novel approach to metabolic flux analysis that avoids error-prone, intuitive, and ad hoc decisions on 13 C rearrangements. In particular, we developed a rigorous approach for deriving reaction reversibilities by combining in vivo intracellular metabolite concentrations with a thermodynamic feasibility analysis. The thus-obtained analytical model of metabolism was then used for network-wide isotopologue balancing to estimate the intracellular fluxes. These 13 C-flux data revealed an extraordinarily high malate influx that is primarily catabolized via the gluconeogenic reactions and toward overflow metabolism. Furthermore, a considerable NADPH-producing malic enzyme flux is required to supply the biosynthetically required NADPH in the presence of malate. Co-utilization of glucose and malate resulted in a synergistic decrease of the respiratory tricarboxylic acid cycle flux.Typically, microbes prefer a single carbon source whose presence represses utilization of alternative substrates. The classical example is the diauxic shift of Escherichia coli with subsequent growth on first glucose and then lactose (1). This widespread phenomenon, referred to as carbon catabolite repression, has been intensively studied in many chemoorganotrophic microbes, and in the vast majority of documented cases, the preferred carbon source is glucose (2, 3). Apart from repressing the co-utilization of alternative substrates, preferred carbon sources are normally associated with a high specific growth rate and substantial secretion of overflow metabolites such as ethanol, lactate, or acetate. For the Grampositive model bacterium Bacillus subtilis, glucose has long been recognized to be preferred, but recent data indicated that glucose might not be the only preferred carbon source (4, 5).According to the current model of the global carbon catabolite repression mechanism in B. subtilis, glucose-induced catabolite repression is mediated by the HPr kinase-catalyzed phosphorylation of HPr at its Ser-46 residue (2). This effect is propagated throughout the cell by the pleiotropic transcription factor CcpA (6), whose binding to the target sites for catabolite repression is controlled by the presence of HPr(Ser...

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Consistency of Scale‐Up from Bioprocess Development to Production

Junne

Klingner

Itzeck

et al. 2012

Biopharmaceutical Production Technology

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The fed -batch technique is the most frequently applied operation mode for an effi cient biotechnological production. It is often characterized by the achievement of higher product yields compared to the batch mode. For the case when the fedbatch process is operated under substrate -limiting conditions, substrate uptake rates lower than the maximum uptake capacities of cells occur. Thus, the accumulation of branch -point intermediate compounds of the cell ' s metabolism is more or less avoided. The synthesis of unwanted side -products is not at all or only supported barely with low amounts of substrate. Usually, under substrate -limiting conditions, carbon is provided for the most important products in order to keep the cellular system functional and viable.Such substrate -limiting conditions are easily achieved at the laboratory scale and pilot scale. Most often, the feed solution is introduced through a pipe at the top of the fermenter. A mixing time of several seconds is achieved in stirred tank reactor s ( STR s), which is so fast that the even distribution of the substrate in the reactor is not disturbed. Hence, even up to high cell densities, no accumulation of unwanted byproducts under fed -batch conditions is observed, except that viscosity is very high and oxygen availability becomes insuffi cient in late process stages. However, this is different in biotechnological production in large -scale fermenters. Due to mechanical and economical limitations of the power input, the mixing time of an STR increases 10 -fold or more when reaching liquid volumes of several cubic meters [1 -3] . This leads to a faster conversion by the microorganisms near the feeding zone, while far away from it production of the substrate ceases with increasing cell concentration. The resulting gradients near the feeding point alter the process performance [4,5] . In particular, substrate excess, which thwarts the idea of a fed -batch process, can lead to the synthesis of unwanted byproducts [6] . Due to the movement of cells in the reactor, they are exposed to ongoing oscillating environmental conditions where they fl ip between substrate excess and 16 Biopharmaceutical Production Technology, First Edition. Edited by Ganapathy Subramanian. Glucose metabolism at high density growth of E. coli B and E. coli K: differences in metabolic pathways are

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Maintenance metabolism and carbon fluxes in Bacillus species

Cited by 68 publications

References 38 publications

Distinct Effects of Sorbic Acid and Acetic Acid on the Electrophysiology and Metabolism of Bacillus subtilis

Distinct Effects of Sorbic Acid and Acetic Acid on the Electrophysiology and Metabolism of Bacillus subtilis

Metabolic Fluxes during Strong Carbon Catabolite Repression by Malate in Bacillus subtilis

Consistency of Scale‐Up from Bioprocess Development to Production

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