Direct contact method of autoradiography was applied in order to know in Eurytrema pancreaticum which was incubated at various intervals such as 60, 120, 240, and 360 minutes in the vitro media added with radioactive succinic acid, C(14)-succinate. The distribution of the radioactive succinate was clarified by this technique and possible explanation was presented. The autoradiographic procedures were essentially the same as those reported previously by Yoon et al. (1964). The most distinct autoradiograms were obtained after 240 minutes incubation. The radioactivity of this labelled succinic acid chiefly concentrated in reproductive organs, such as testes, ovary, egg containing uterine tubules and vitelline follicles.
paraisology-helminth-trematoda-Eurytrema pancreaticum ; autoradiography ; metabolism-succinic acid ; succinic acid

The production of 2, 3-butanediol and succinic acid by a moderate halophile under anaerobic condition was investigated. This halophile, termed Salinivibrio YS, was isolated from the solid samples collected from Aydingkol Lake. Based on the single factor experiment, the parameters and their values for the production were obtained. Then, the optimum values of these parameters by the orthogonal experiments were obtained: temperature, 33 degrees C; initial pH of fermentation, 8.0; the pH during fermentation, 7.0; the concentration of acetic acid was 3 g/L and NaC1 was 10 g/L. Finally, a 3-L fermentation based on these conditions was carried out. After 108 h of fermentation under anaerobic condition, 35.05 g/L of 2, 3-butanediol and 22.46 g/L of succinic acid were obtained. About 50% of total glucose conversion was achieved. The study on 2, 3-butanediol and succinic acid by a halophile under anaerobic condition will expand the applications of halophiles and open a new area of production of 2, 3-butanediol and succinic acid.
Anaerobiosis ; Butylene Glycols ; metabolism ; Fermentation ; Halobacteriales ; metabolism ; Succinic Acid ; metabolism ; Vibrionaceae ; metabolism

The possibility of reusing Escherichia coli cells from the broth for succinic acid production was investigated. Using succinic acid yield and productivity as criterion, we investigated the effects of cell concentration, initial glucose concentration, different neutralizers on the bioconversion. The results revealed that E. coli could convert glucose to succinic acid in a water solution of glucose and a neutralizer. According to the results, the optimal condition was as follows: the cell concentration was 50 (OD600), glucose concentration was 40 g/L and neutralizer was MgCO3. Under the optimum conditions, we carried out the consecutive batch bioconversion in 7 L fermenter. Succinic acid yield reached 91% with the productivity of 3.22 g/(L x h) for the first conversion. For the second conversion, succinic acid yield reached 86% with productivity of 2.04 g/(L x h). Furthermore, we achieved a high mass yield above 83% with the productivity of 1.82 g/(L x h) for the third bioconversion.
Escherichia coli ; genetics ; metabolism ; Fermentation ; Genetic Engineering ; Glucose ; metabolism ; Industrial Microbiology ; Succinic Acid ; metabolism

We investigated the effect of adding intermediate metabolites on cell growth and succinate production. The yield of succinic acid achieved to the highest when 0.5 g/L phosphoenolpyruvic acid (PEP) was added. According to the metabolic network of Actinobaccilus succinogenes NJ113, the metabolic flux was calculated by metabolic flux analysis. The ratio of hexose monophosphate pathway to glycolytic pathway increased from 39.4:60.3 to 76.8:22.6 after adding 0.5 g/L PEP, thus the reducing power was better balanced. The flux of PEP to oxaloacetate was 23.8% higher, which made the succinic acid flux improve from 99.8 mmol/(g DCW x h) to 124.4 mmol/(g DCW x h) and the flux of acetic acid and formic acid decreased by 22.9% and 15.4%, respectively. The key enzyme activity analysis showed that the specific activity of PEP carboxykinase reached to 1910 U/mg with 0.5 g/L PEP addition, which was 74.7% higher than the control; and the specific activity of pyruvate kinase decreased by 67.5%. Finally, the concentration of succinic acid was 29.1 g/L with the yield of 76.2%.
Actinobacillus ; metabolism ; Anaerobiosis ; Culture Media ; Culture Techniques ; methods ; Fermentation ; Phosphotransferases (Paired Acceptors) ; metabolism ; Succinic Acid ; metabolism

Spent cells recovered from anaerobic fermentation by Actinobacillus succinogenes were used as nitrogen source for succinic acid production. Three methods were investigated for cell wall-breaking. The results showed that enzymatic hydrolysis was more effective for higher succinic acid yield. When the enzymatic hydrolysate of spent cells was added to reach a total nitrogen concentration 1.11 g/L (equivalent to 10 g/L yeast extract), the succinic acid concentration was 42.0 g/L, but it increased slightly when enhancing the level of enzymatic hydrolysate. However, when 5 g/L yeast extract was supplemented with the enzymatic hydrolysate of spent cells, the succinic acid concentration reached 75.5 g/L after 36 hours and, the succinic acid productivity was 2.10 g/(L x h), which increased by 66.7% compared with the fermentation using 10 g/L yeast extract. Therefore, enzymatic hydrolysate of spent cells could replace 50% yeast extract in the original medium for succinic acid production.
Actinobacillus ; metabolism ; Anaerobiosis ; Culture Media ; pharmacology ; Fermentation ; Industrial Waste ; Succinic Acid ; metabolism

Succinic acid is an important C4 platform chemical in the synthesis of many commodity and special chemicals. In the present work, different compounds were evaluated for succinic acid production by Actinobacillus succinogenes GXAS 137. Important parameters were screened by the single factor experiment and Plackeet-Burman design. Subsequently, the highest production of succinic acid was approached by the path of steepest ascent. Then, the optimum values of the parameters were obtained by Box-Behnken design. The results show that the important parameters were glucose, yeast extract and MgCO3 concentrations. The optimum condition was as follows (g/L): glucose 70.00, yeast extract 9.20 and MgCO3 58.10. Succinic acid yield reached 47.64 g/L at the optimal condition. Succinic acid increased by 29.14% than that before the optimization (36.89 g/L). Response surface methodology was proven to be a powerful tool to optimize succinic acid production.
Actinobacillus ; classification ; genetics ; metabolism ; Bioreactors ; Culture Media ; metabolism ; Fermentation ; Glucose ; metabolism ; Industrial Microbiology ; methods ; Succinic Acid ; metabolism

To understand the effects of sugar whose uptake is dependent or independent on the phosphotransferase system (PTS), two-stage culture of Escherichia coli strain NZN111 that was constructed by disruption of IdhA and pflB encoding the fermentative lactate dehydrogenase (LDH) and pyruvate: formate lyase (PFL) of E. coli W1485, was carried out for organic acids production. When NZN111 was aerobically cultured on fructose (PTS dependent) or maltose (PTS independent), it fermented glucose with succinic acid and pyruvic acid as the major products in subsequent anaerobic culture. The experiments were also performed in a 5-L fermentor. The yields of succinic acid by the fructose-and maltose-grown NZN111 were 0.84 and 0.75 mol/mol, whereas the yields of pyruvic acid were 0.65 and 0.83 mol/mol, respectively. The final ratio of succinic acid to pyruvic acid in the anaerobic stage reached 1.73:1 and 1.21:1, respectively. The different behaviors in anaerobic fermentation by the fructose-, maltose- and glucose-grown NZN111 were likely caused by the regulation of catabolite repression in the aerobic culture stage.
Aerobiosis ; Anaerobiosis ; Carbon ; metabolism ; Escherichia coli ; classification ; metabolism ; Fermentation ; Fructose ; metabolism ; Maltose ; metabolism ; Phosphotransferases ; metabolism ; Pyruvic Acid ; metabolism ; Succinic Acid ; metabolism

Succinic acid has received a great deal of attention as an important green chemical stock for the manufacture of synthetic resins, biodegradable polymers and chemical intermediates. In this paper, the breeding mechanism of Actinobacillus succinogenes based on metabolic flux analysis was demonstrated to improve the yield of succinic acid by fermentation. After the NTG treatment, mutants from A. succinogenes CGMCC 1593 which were able to grow in medium containing concentrations of about 50-100 mmol/L of sodium monofluoroacetate were obtained. Among them, a mutant SF-9 was selected for producing more succinic acid and less acetic acid. When fermentations were conducted in a 5 L bioreactors, the final succinic acid concentration of SF-9 (34.8 g/L) increased 23.4%, and the mass ratio of succinic acid/acetic acid increased from 3.3 to 9 compared with those of the parent strain. Based on the metabolic flux analysis of A. succinogenes, PEP was found to be a key node which has an important effect on the production of succinic acid, and the flux ratio of by-productions (acetic, formic, lactic acid) was influenced by PYR node. Compared with the parent strain, the flux to succinic acid of mutant (A. succinogenes SF-9) was significantly increased, while the flux to by-productions had an obvious decline. Therefore, PEP and PYR are not rigid nodes in the metabolic regulation of A. succinogenes.
Actinobacillus ; genetics ; growth & development ; metabolism ; Drug Tolerance ; Fermentation ; Fluoroacetates ; metabolism ; Metabolic Networks and Pathways ; Mutation ; Succinic Acid ; metabolism

Escherichia coli AFP111 is a spontaneous mutant with mutations in the glucose specific phosphotransferase system (ptsG) in NZN111 (delta pflAB deltaldhA). In AFP111, conversion of xylose to succinic acid generates 1.67 molecule of ATP per xylose. However, the strain needs 2.67 molecule ATP for xylose metabolism. Therefore, AFP111 cannot use xylose due to insufficient ATP under anaerobic condition. Through an atmospheric and room temperature plasma (ARTP) jet, we got a mutant strain named DC111 that could use xylose under anaerobic condition in M9 medium to produce succinic acid. After 72 h, DC111 consumed 10.52 g/L xylose to produce 6.46 g/L succinic acid, and the yield was 0.78 mol/mol. Furthermore, the reaction catalyzed by the ATP-generating PEP-carboxykinase (PCK) was enhanced. The specific activity of PCK was 19.33-fold higher in DC111 than that in AFP111, which made the strain have enough ATP to converse xylose to succinic acid.
Atmosphere ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Industrial Microbiology ; Metabolic Engineering ; Mutation ; Plasma Gases ; pharmacology ; Succinic Acid ; metabolism ; Temperature ; Xylose ; metabolism

During the anaerobic fermentation by Escherichia coli AFP111 for succinic acid production, the viable cell concentration and productivity were decreased with the raising of succinic acid concentration. In order to restore cellular succinic acid productivity and prolong fermentation time, we collected strains and refreshed medium for repetitive succinic acid production. However, productivity is lower than that in the anaerobic fermentation before reusing strains. To enhance the productivity, strains were aerobically cultivated for 3 h in pure water before anaerobic fermentation. The activities of key enzymes were enhanced for better performance in producing succinic acid at anaerobic stage. After three rounds of repetitive fermentations, succinic acid concentration and yield reached to 56.50 g/L and 90% respectively. The succinic acid productivity was 0.81 g/(L x h), which was 13% higher than the repetitive fermentations without aerobic activation of the strains.
Aerobiosis ; Anaerobiosis ; Culture Media ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Genetic Engineering ; Glucose ; metabolism ; Industrial Microbiology ; Succinic Acid ; metabolism