Chemically assisted microbial production of succinic acid by the yeast Yarrowia lipolytica grown on ethanol.

A new two-step process of production of succinic acid (SA) has been developed, which includes the microbial synthesis of alpha-ketoglutaric acid by the yeast Yarrowia lipolytica (step 1) and subsequent oxidation of the acid by hydrogen peroxide to SA (step 2). The maximum concentration of SA and its yield were found to be 63.4 g l(-1) and 58% of the ethanol consumed, respectively.

Citric acid production patent review.

Current Review article summarizes the developments in citric acid production technologies in East and West last 100 years. Citric acid is commercially produced by large scale fermentation mostly using selected fungal or yeast strains in aerobe bioreactors and still remains one of the runners in industrial production of biotechnological bulk metabolites obtained by microbial fermentation since about 100 years, reflecting the historical development of modern biotechnology and fermentation process technology in East and West. Citric acid fermentation was first found as a fungal product in cultures of Penicillium glaucum on sugar medium by Wehmer in 1893.

[Obtaining of the mutant Yarrowia lipolytica strains producing citric acid from glucose].

The possibility of obtaining mutant yeasts Yarrowia lipolytica VKM Y-2373 with increased ability to synthesize citric acid from glucose by using UV irradiation and N-methyl-NT-nitro-N-nitrosoguanidine was studied. Of 1500 colonies of the Y. lipolytica treated with either UV or N-methyl-NT-nitro-N-nitrosoguanidine, three mutants were selected that displayed higher (by 23%) biosynthetic ability as compared with the initial strain.

[Synthesis citric and isocitric acids by Yarrowia lipolytica during yeasts growth on rapeseed oils].

The native strain Yarrowia lipolytica VKM Y-2373 grown in a complete medium exhibited the maximum lipase activity at the concentration of rapeseed oil of at least 5.0 g/l. In the course of yeast growth, no considerable changes were observed in the glycerol concentration, the proportions of the major free fatty acids formed via oil hydrolysis, or the fatty acid composition of oil.

Evolution of glyoxylate cycle enzymes in Metazoa: evidence of multiple horizontal transfer events and pseudogene formation.

Background: The glyoxylate cycle is thought to be present in bacteria, protists, plants, fungi, and nematodes, but not in other Metazoa. However, activity of the glyoxylate cycle enzymes, malate synthase (MS) and isocitrate lyase (ICL), in animal tissues has been reported. In order to clarify the status of the MS and ICL genes in animals and get an insight into their evolution, we undertook a comparative-genomic study.

[The effect of succinate on respiration, transamination, and pyruvate formation in cells of the yeast Dipodascus magnusii].

The effect of succinate on the growth and respiration of the yeast Dipodascus magnusii VKM Y-1072, which is auxotrophic for thiamine and biotin, was studied. The addition of succinate to a culture grown on glucose was found to activate the respiration of cells on various substrates by enhancing the processes related to transamination reactions. In this case, aerobic fermentation (ethanol production) decreased, whereas pyruvate production increased.

[Ethanol metabolism in the yeasts Yarrowia and Torulopsis (a review)].

Results of research into ethanol metabolism in yeast organisms with highly pronounced aerobic metabolism are reviewed. The low activity of NAD-dependent alcohol dehydrogenase (EC 1.1.

[Organic acid production by the yeast Yarrowia lipolytica (a review)].

The review sums up the results of studies of (1) physiological growth characteristics of the yeast Yarrowia lipolytica, cultured in the presence of diverse carbon sources (n-alkanes, glucose, and glycerol), and (2) superhigh synthesis of organic acids, which were performed at the Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences. Microbiological processes of obtaining alpha-ketoglutaric, pyruvic, isocitric, and citric acids are discussed.

Evidence of the glyoxylate cycle in the liver of newborn rats.

Background: It is generally accepted that the glyoxylate cycle exists in microorganisms and higher plants but absent in higher animals. the hypodhesis of the glyoxylate cycle in the tissues of higher animals with a high level of physiological activity was first proposed by Kondrashova and Rodionova in 1971. The goal of this work was yo verifv this in newborn rats, which possess a 2.

Regulation of NAD(+)-dependent isocitrate dehydrogenase in the citrate producing yeast Yarrowia lipolytica.

The mechanism of the increased accumulation (overproduction) of citric acids in the yeast Yarrowia lipolytica while growing in the presence of glucose under nitrogen deficiency was investigated. The limitation of the yeast growth by the source of nitrogen decreases the total content of nucleotides and increases the ratios of ATP/AMP and NADH/NAD+. NAD+-Dependent isocitrate dehydrogenase, an enzyme of the tricarboxylic acid cycle playing a key role in the regulation of biosynthesis of citric and isocitric acids, was isolated from Y.

[The isolation, purification, and some properties of NAD-dependent isocitrate dehydrogenase from the organic acid-producing yeast Yarrowia lipolytica].

The NAD+-dependent isocitrate dehydrogenase of the organic acid-producing yeast Yarrowia lipolytica was isolated, purified, and partially characterized. The purification procedure included four steps: ammonium sulfate precipitation, acid precipitation, hydrophobic chromatography, and gel-filtration chromatography. The enzyme was purified 129-fold with a yield of 31% and had a specific activity of 22 U/mg protein.

[Biochemical characterization of the yeast Yarrowia lipolytica overproducing carboxylic acids from ethanol. Nitrogen metabolism enzymes].

A comparative assay of nitrogen metabolism enzymes in the Yarrowia lipolytica mutant N1 grown under conditions promoting the overproduction of either alpha-ketoglutaric acid (KGA) or citric acid showed that the overproduction of KGA correlates with an increase in the activities of the NAD- and NADP-linked glutamate dehydrogenase, glutamic-pyruvic transaminase, and glutamic-oxaloacetic transaminase reactions. These reactions are likely to be responsible for the overproduction of KGA by this mutant. In contrast, the overproduction of citric acid correlated with a decline in the activities of the NAD- and NADP-linked glutamate dehydrogenases and with an increase in the activities of glutamine synthetase and glutamate synthase.

[Induction of cytochrome P-450 and ethanol oxidation in Yarrowia lipolytica].

The study of the effect of different ethanol concentrations in the medium on the growth and the activity of enzymatic systems involved in ethanol oxidation in Yarrowia lipolytica showed that the cultivation of yeast cells on 1 and 2% ethanol caused their rapid growth and a drastic increase in cell respiration and sensitivity to cyanide already in the first hours of cultivation. At the same time, during cultivation on 3, 4, and 5% ethanol, the growth and respiration of yeast cells were considerably suppressed. All of the ethanol concentrations studied induced the synthesis of cytochrome P-450, its dynamics in cells being dependent on the initial concentration of ethanol in the medium.

Oxygen requirements for growth and citric acid production of Yarrowia lipolytica.

During continuous cultivation of Yarrowia lipolytica N 1, oxygen requirements for growth and citric acid synthesis were found to depend on the iron concentration in the medium. A coupled effect of oxygen and iron concentrations on the functioning of the mitochondrial electron transport chain in Y. lipolytica N 1 was established.

Biosynthesis of citric and isocitric acids from ethanol by mutant Yarrowia lipolytica N 1 under continuous cultivation.

The effect of ethanol, zinc, and iron (Fe(2+) and Fe(3+)) concentration and of oxygen supply on cell growth and the production of citric acid (CA) and isocitric acid (ICA) from ethanol by mutant Yarrowia lipolytica N 1 was studied under continuous cultivation. The following peculiarities of Y. lipolytica metabolism were found: (1) intensive CA production occurred under yeast growth limitation by nitrogen; (2) inhibition of yeast growth by ethanol was accompanied by significant alterations in fatty acid composition of lipids; (3) the production of CA and ICA from ethanol required high concentrations of zinc and iron ions; (4) the intracellular iron concentration determined whether CA or ICA was predominantly formed; (5) the cell's requirement for oxygen depended on the intracellular iron concentration.

[Metabolism of Yarrowia lipolytica grown on ethanol under conditions promoting the production of alpha-ketoglutaric and citric acids: a comparative study of the central metabolism enzymes].

A comparative study of the enzymes of the tricarboxylic acid (TCA) and glyoxylate cycles in the mutant Yarrowia lipolytica strain N1 capable of producing alpha-ketoglutaric acid (KGA) and citric acid showed that almost all enzymes of the TCA cycle are more active under conditions promoting the production of KGA. The only exception was citrate synthase, whose activity was higher in yeast cells producing citric acid. The production of both acids was accompanied by suppression of the glyoxylate cycle enzymes.

[Metabolic characteristics of the Yarrowia lipolytica strain producing alpha-ketoglutaric and citric acids from ethanol and the effect of [NH4+] and [O2] on yeast respiration and biosynthesis].

The comparative studies performed in this work showed that overproduction of alpha-ketoglutaric acid (KGA) from ethanol by the mutant Yarrowia lipolytica strain I requires both a deficiency of thiamine and a relatively high concentration of ammonium ions in the medium, whereas CA overproduction requires an almost zero concentration of ammonium ions. The threshold value of the dissolved oxygen concentration in the medium, pO2, for CA overproduction is considerably higher than for KGA overproduction. The respiration rate of CA-overproducing cells was 2-3.

Mathematical modeling of citric acid production by repeated batch culture.

A mathematical model has been created for the process of citric acid biosynthesis by yeast (mutant strain Yarrowia lipolytica) cultivated by the repeated batch (RB) method on ethanol under conditions of nitrogen limitation. The model accounts for cell growth as a function of nitrogen concentration in the culture liquid; nitrogen uptake by growing cells; citric acid production; pH control in the fermentor by means of NaOH addition; and changes in system volume. The model represents a system of five nonlinear differential equations.

Biosynthesis of citric acid by Yarrowia lipolytica repeat-batch culture on ethanol.

After analysis of batch culture and identification of the ways for prolongation of citric acid active synthesis by yeast, repeat-batch (RB) cultivation was suggested. Yarrowia lipolytica strain RB cultivation was studied and optimal conditions for cultivation selected. It was shown that when applying RB cultivation, better results were obtained than for batch cultivation.

Synthesis of alpha-ketoglutaric acid by Yarrowia lipolytica yeast grown on ethanol.

The ability of yeast to synthesize alpha-ketoglutaric acid (KGA) from ethanol has been studied. Thiamine-auxotrophic yeasts of different genera and species may be able to produce KGA; the main condition of synthesis is growth limitation by thiamine. Using a model culture, mutant Yarrowia lipolytica N 1, the principal conditions affecting KGA oversynthesis were identified.

Change in transport activities of vacuoles of the yeast Yarrowia lipolytica during its growth on glucose.

Vacuoles were isolated from Yarrowia lipolytica yeast cells taken at various growth phases under carbon or nitrogen limitation. Vacuoles from the cells at the logarithmic growth phase showed a high activity of vacuolar H(+)-ATPase (0.9-1.

[Changes in the lungs in the early period of closed trauma of the thorax in rats].

In experiments on rats it has been demonstrated that in the acute period of uninjured parts of the lungs periodic changes of protein, lipid and glucose concentrations developed. In uninjured parts of the lungs one can observe more concentration of lipids and in injured parts-more glucose. The changes of substrates, concentrations in the lungs are due to not only the changes of venous blood excess in the lungs, but are connected with metabolic changes in the cells of the injured and uninjured parts of the lungs.

[Comparative study of Candida lipolytica yeasts with various abilities to produce citrate].

The growth and the activity of some enzymes were studied in a Candida lipolytica strain 12a which did not synthesize acids in a medium with glucose under the conditions of nitrogen deficiency. The substrate was not assimilated and cyanide-resistant respiration did not develop in the strain under the conditions of profound nitrogen deficiency. The inability of cells to assimilate glucose at the stationary phase of growth resulted, apparently, from an abrupt decrease of phosphofructokinase and pyruvate dehydrogenase activities in the cells.