Influence of environmental and nutritional factors on succinic acid production and enzymes of reverse tricarboxylic acid cycle from Enterococcus flavescens

2007 ◽  
Vol 40 (4) ◽  
pp. 629-636 ◽  
Author(s):  
Lata Agarwal ◽  
Jasmine Isar ◽  
Gautam K. Meghwanshi ◽  
Rajendra Kumar Saxena
Keyword(s):  
Succinic Acid ◽  
Acid Production ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Nutritional Factors ◽  
Acid Cycle ◽  
Succinic Acid Production

Effect of process parameters on succinic acid production in Escherichia coli W3110 and enzymes involved in the reductive tricarboxylic acid cycle

2006 ◽  
Vol 52 (9) ◽  
pp. 893-902 ◽  
Author(s):  
Jasmine Isar ◽  
Lata Agarwal ◽  
Saurabh Saran ◽  
Pritesh Gupta ◽  
Rajendra Kumar Saxena
Keyword(s):  
Escherichia Coli ◽  
Succinic Acid ◽  
Process Optimization ◽  
Enzyme Activities ◽  
Acid Production ◽  
Tricarboxylic Acid Cycle ◽  
Sucrose Concentration ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Succinic Acid Production

The effect of process optimization on succinic acid production by Escherichia coli W3110 and on enzymes involved in the reverse tricarboxylic acid cycle was studied. Approximately, 7.02 g L–1 of succinic acid was produced in 60 h at pH 7.0 in 500 mL anaerobic bottles containing 300 mL of the medium, wherein the sucrose concentration was 2.5%, the ratio of tryptone to ammonium hydrogen phosphate was 1:1, and the concentration of magnesium carbon ate was 1.5%. When these optimized fermentation conditions were employed in a 10 L bioreactor, 11.2 g L–1 of succinic acid was produced in 48 h. This is a 10-fold increase in succinic acid production from the initial titer of 0.94 g L–1. This clearly indicates the importance of process optimization, where by manipulating the media composition and production conditions, a remarkable increase in the production of the desired biomolecule can be obtained. The production of succinic acid is a multi-step reaction through the reverse tricarboxylic acid cycle. A linear relationship was observed between succinic acid production and the enzyme activities. The enzyme activities were found to increase in the order phospho-enol-pyruvate carboxylase < malate dehydrogenase < fumarase < fumarate reductase. The activity of phospho-enol-pyruvate carboxykinase was also estimated. Results indicate that this enzyme was not a very active participant in the production of succinic acid, since it catalyzes the phosphorylation of oxaloacetic acid to yield phospho-enol-pyruvate.Key words: anaerobic production, succinic acid, Escherichia coli, process optimization, reverse tricarboxylic acid cycle enzymes, fermentation.

THE METABOLISM OF PUTRESCINE (1,4-DIAMINOBUTANE) BY MYCOBACTERIA ISOLATED FROM FISH: II. STUDIES WITH ARSENITE-INHIBITED CELLS AND CELL-FREE EXTRACTS

1967 ◽  
Vol 13 (5) ◽  
pp. 521-531 ◽  
Author(s):  
T. P. T. Evelyn
Keyword(s):  
Succinic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Significant Proportion ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Aminobutyric Acid ◽  
Succinic Semialdehyde ◽  
Amino Group ◽  
Intact Cells ◽  
Acid Cycle

Three mycobacterial strains isolated from fish degraded putrescine by a pathway in which γ-aminobutyraldehyde (Δ′-pyrroline), γ-aminobutyric acid, succinic semialdehyde, and succinic acid were intermediates. These results agree substantially with those of other workers using different microorganisms. Intact cells utilized γ-aminobutyric acid in a transaminase reaction with endogenously supplied α-ketoglutarate to produce succinic semialdehyde and glutamate. Studies with arsenite-poisoned cells showed that a significant proportion of putrescine was metabolized via pyruvate and alanine. When putrescine-1,4-14C was substrate, HCl extracts of cells contained radioactive aspartate and glutamate in addition to alanine. The further metabolism of succinate therefore proceeded in two directions: one yielding oxalacetate and α-ketoglutarate by way of the tricarboxylic acid cycle, and the other branching off the cycle to yield pyruvate. Studies with cell-free extracts suggested that putrescine nitrogen was assimilated via glutamate, which served as the amino-group donor to yield alanine and aspartate.

Substrate-dependent alteration in O2 consumption and energy metabolism in vascular smooth muscle

1996 ◽  
Vol 270 (6) ◽  
pp. H1869-H1877 ◽  
Author(s):  
J. T. Barron ◽  
S. J. Kopp ◽  
J. Tow ◽  
J. E. Parrillo
Keyword(s):  
Smooth Muscle ◽  
Lactic Acid ◽  
Energy Metabolism ◽  
Vascular Smooth Muscle ◽  
Acid Production ◽  
Tricarboxylic Acid Cycle ◽  
Lactic Acid Production ◽  
Tricarboxylic Acid ◽  
O2 Consumption ◽  
Acid Cycle

Energy metabolism and the substrate utilization pattern of intact porcine carotid artery were investigated in the presence or absence of glucose and/or octanoate during the phases of isometric contraction induced by K+ depolarization. During the early phase of contraction, there was a rapid increase in the rate of O2 uptake that was independent of the rate of force generation but dependent on the availability of intracellular pyruvate, the source of which was glucose and not glycogen. Lactate production increased linearly from the onset of contractile stimulation and was not suppressed by octanoate oxidation. There was no alteration from the basal resting state in the concentrations of the metabolites of the tricarboxylic acid cycle in the presence or absence of octanoate. During the phase of steady-state force maintenance, O2 consumption was increased compared with the basal unstimulated rate but was not increased when glucose and octanoate were present, which is consistent with the Crabtree effect. This was associated with increased aerobic lactic acid production and inhibition of the tricarboxylic acid cycle at the citrate synthase step. Alteration of the high-energy phosphate content could not account for the pattern of O2 consumption during contraction under different substrate conditions. In the absence of glucose, the energy from octanoate oxidation could substitute for the energy ordinarily derived from aerobic glycogen and lactic acid production. It is concluded that energy metabolism of vascular smooth muscle is coordinated during contraction by integration of the pathways of aerobic glycolysis and oxidative phosphorylation.

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