scholarly journals Forever panting and forever growing: physiology of Saccharomyces cerevisiae at extremely low oxygen availability in the absence of ergosterol and unsaturated fatty acids

2019 ◽  
Vol 19 (6) ◽  
Author(s):  
Bruno Labate Vale da Costa ◽  
Vijayendran Raghavendran ◽  
Luís Fernando Mercier Franco ◽  
Adriano de Britto Chaves Filho ◽  
Marcos Yukio Yoshinaga ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Laboratory Strain ◽  
Glucose Consumption ◽  
Continuous Cultivation ◽  
Low Ph ◽  
Anaerobic Growth ◽  
Low Oxygen ◽  
Lipid Fatty Acid

ABSTRACT We sought to investigate how far the growth of Saccharomyces cerevisiae under full anaerobiosis is dependent on the widely used anaerobic growth factors (AGF) ergosterol and oleic acid. A continuous cultivation setup was employed and, even forcing ultrapure N2 gas through an O2 trap upstream of the bioreactor, neither cells from S. cerevisiae CEN.PK113–7D (a lab strain) nor from PE-2 (an industrial strain) washed out after an aerobic-to-anaerobic switch in the absence of AGF. S. cerevisiae PE-2 seemed to cope better than the laboratory strain with this extremely low O2 availability, since it presented higher biomass yield, lower specific rates of glucose consumption and CO2 formation, and higher survival at low pH. Lipid (fatty acid and sterol) composition dramatically altered when cells were grown anaerobically without AGF: saturated fatty acid, squalene and lanosterol contents increased, when compared to either cells grown aerobically or anaerobically with AGF. We concluded that these lipid alterations negatively affect cell viability during exposure to low pH or high ethanol titers.

scholarly journals Anaerobic growth of Saccharomyces cerevisiae CEN.PK113-7D does not depend on synthesis or supplementation of unsaturated fatty acids

2019 ◽  
Vol 19 (6) ◽  
Author(s):  
Wijb J C Dekker ◽  
Sanne J Wiersma ◽  
Jonna Bouwknegt ◽  
Christiaan Mooiman ◽  
Jack T Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Laboratory Strain ◽  
Tween 80 ◽  
Batch Cultivation ◽  
Anaerobic Growth ◽  
Growth Media ◽  
Yeast Viability

ABSTRACT In Saccharomyces cerevisiae, acyl-coenzyme A desaturation by Ole1 requires molecular oxygen. Tween 80, a poly-ethoxylated sorbitan-oleate ester, is therefore routinely included in anaerobic growth media as a source of unsaturated fatty acids (UFAs). During optimization of protocols for anaerobic bioreactor cultivation of this yeast, we consistently observed growth of the laboratory strain S. cerevisiae CEN.PK113-7D in media that contained the anaerobic growth factor ergosterol, but lacked UFAs. To minimize oxygen contamination, additional experiments were performed in an anaerobic chamber. After anaerobic precultivation without ergosterol and Tween 80, strain CEN.PK113-7D and a congenic ole1Δ strain both grew during three consecutive batch-cultivation cycles on medium that contained ergosterol, but not Tween 80. During these three cycles, no UFAs were detected in biomass of cultures grown without Tween 80, while contents of C10 to C14 saturated fatty acids were higher than in biomass from Tween 80-supplemented cultures. In contrast to its UFA-independent anaerobic growth, aerobic growth of the ole1Δ strain strictly depended on Tween 80 supplementation. This study shows that the requirement of anaerobic cultures of S. cerevisiae for UFA supplementation is not absolute and provides a basis for further research on the effects of lipid composition on yeast viability and robustness.

scholarly journals Fatty-acid desaturation and microsomal lipid fatty-acid composition in experimental hyperthyroidism

1981 ◽  
Vol 193 (3) ◽  
pp. 845-852 ◽  
Author(s):  
F H Faas ◽  
W J Carter
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Food Intake ◽  
Acid Composition ◽  
Unsaturated Fatty Acids ◽  
Fatty Acid Desaturation ◽  
Experimental Hyperthyroidism ◽  
Lipid Fatty Acid ◽  
Hormone Effect ◽  
Lipid Fatty Acid Composition

We have studied the influence of experimental hyperthyroidism in the rat on the synthesis of unsaturated fatty acids and on liver microsomal lipid fatty-acid composition. Tri-iodothyronine treatment (25 micrograms/100 g body weight) daily for 3 weeks caused no significant changes in delta 9 (stearate) desaturation but a 24% decrease in delta 6 (linoleate) desaturation. Much larger doses of tri-iodothyronine increased delta 9 desaturation. Liver microsomal fatty-acid composition in hyperthyroidism is altered with significantly increased proportions of stearate and arachidonate and decreased proportions of palmitate, palmitoleate, linoleate (C18:2) and eicosa-8,11,14-trienoate (C20:3). These changes, other than the decreases proportion of C20:3 fatty acid, which may be due to the diminished delta 6 desaturase activity, cannot be attributed to changes in fatty-acid desaturation. Most of these changes were also found to be due not simply to the decreased weight gain or the increased food intake of the hyperthyroid animals. Only the decreased C18:2 fatty-acid proportions could be mimicked by restricting food intake of control animals and none of the changes were prevented by restricting food intake of hyperthyroid animals. Thus most of the changes in microsomal lipid fatty-acid composition are likely to be due to a thyroid hormone effect on peripheral lipid mobilization or lipid degradation.

scholarly journals Oxygen Consumption by Anaerobic Saccharomyces cerevisiae under Enological Conditions: Effect on Fermentation Kinetics

2003 ◽  
Vol 69 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Eric Rosenfeld ◽  
Bertrand Beauvoit ◽  
Bruno Blondin ◽  
Jean-Michel Salmon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Oxygen Consumption ◽  
Stationary Phase ◽  
Respiratory Chain ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Anaerobic Growth ◽  
Fermentation Rate ◽  
Fermentation Kinetics ◽  
Oxygen Pulse

ABSTRACT The anaerobic growth of the yeast Saccharomyces cerevisiae normally requires the addition of molecular oxygen, which is used to synthesize sterols and unsaturated fatty acids (UFAs). A single oxygen pulse can stimulate enological fermentation, but the biochemical pathways involved in this phenomenon remain to be elucidated. We showed that the addition of oxygen (0.3 to 1.5 mg/g [dry mass] of yeast) to a lipid-depleted medium mainly resulted in the synthesis of the sterols and UFAs required for cell growth. However, the addition of oxygen during the stationary phase in a medium containing excess ergosterol and oleic acid increased the specific fermentation rate, increased cell viability, and shortened the fermentation period. Neither the respiratory chain nor de novo protein synthesis was required for these medium- and long-term effects. As de novo lipid synthesis may be involved in ethanol tolerance, we studied the effect of oxygen addition on sterol and UFA auxotrophs (erg1 and ole1 mutants, respectively). Both mutants exhibited normal anaerobic fermentation kinetics. However, only the ole1 mutant strain responded to the oxygen pulse during the stationary phase, suggesting that de novo sterol synthesis is required for the oxygen-induced increase of the specific fermentation rate. In conclusion, the sterol pathway appears to contribute significantly to the oxygen consumption capacities of cells under anaerobic conditions. Nevertheless, we demonstrated the existence of alternative oxygen consumption pathways that are neither linked to the respiratory chain nor linked to heme, sterol, or UFA synthesis. These pathways dissipate the oxygen added during the stationary phase, without affecting the fermentation kinetics.

scholarly journals Expressing a cytosolic pyruvate dehydrogenase complex to increase free fatty acid production in Saccharomyces cerevisiae

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Yiming Zhang ◽  
Mo Su ◽  
Ning Qin ◽  
Jens Nielsen ◽  
Zihe Liu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Pyruvate Dehydrogenase ◽  
Unsaturated Fatty Acids ◽  
Pyruvate Dehydrogenase Complex ◽  
Cell Factory ◽  
Acetyl Coa ◽  
Fatty Acid Production

Abstract Background Saccharomyces cerevisiae is being exploited as a cell factory to produce fatty acids and their derivatives as biofuels. Previous studies found that both precursor supply and fatty acid metabolism deregulation are essential for enhanced fatty acid synthesis. A bacterial pyruvate dehydrogenase (PDH) complex expressed in the yeast cytosol was reported to enable production of cytosolic acetyl-CoA with lower energy cost and no toxic intermediate. Results Overexpression of the PDH complex significantly increased cell growth, ethanol consumption and reduced glycerol accumulation. Furthermore, to optimize the redox imbalance in production of fatty acids from glucose, two endogenous NAD+-dependent glycerol-3-phosphate dehydrogenases were deleted, and a heterologous NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase was introduced. The best fatty acid producing strain PDH7 with engineering of precursor and co-factor metabolism could produce 840.5 mg/L free fatty acids (FFAs) in shake flask, which was 83.2% higher than the control strain YJZ08. Profile analysis of free fatty acid suggested the cytosolic PDH complex mainly resulted in the increases of unsaturated fatty acids (C16:1 and C18:1). Conclusions We demonstrated that cytosolic PDH pathway enabled more efficient acetyl-CoA provision with the lower ATP cost, and improved FFA production. Together with engineering of the redox factor rebalance, the cytosolic PDH pathway could achieve high level of FFA production at similar levels of other best acetyl-CoA producing pathways.

scholarly journals Ripening and Solar Exposure Alter Polar Lipid Fatty Acid Composition of `Honey Dew' Muskmelons

HortScience ◽  
1990 ◽  
Vol 25 (10) ◽  
pp. 1262-1264 ◽  
Author(s):  
Charles F. Forney
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Solar Radiation ◽  
Acid Composition ◽  
Polar Lipid ◽  
Unsaturated Fatty Acids ◽  
Polar Lipids ◽  
Solar Exposure ◽  
Lipid Fatty Acid

Polar lipids were extracted from immature through overripe `Honey Dew' muskmelons (Cucumis melo L.) that were exposed to high or low levels of solar radiation. Fatty acid composition of the polar lipids changed and the percentage of unsaturated fatty acids increased as fruit ripened. The percentage of monounsaturated fatty acids palmitoleic and oleic acid as a percent of total fatty acids increased from 8% in melons of minimum maturity to >50% in overripe melons. Also, the ratio of unsaturated to saturated fatty acids increased from 2.2 to 5.0. Total polar lipid fatty acid compostion from middle mesocarp tissue (flesh) did not change as much during ripening as the polar lipid composition from the epidermis (peel). Peel tissue from the top of melons relative to the ground had unsaturation ratios of C18 fatty acids and C16 fatty acids 33% and 62% greater, respectively, than peel from the bottom of the melon. Melons of minimum maturity exposed to solar radiation had significantly more unsaturated C18 fatty acids than shaded melons. Increase in the percentage of unsaturated polar lipid fatty acids in `Honey Dew' melons may relate to increases in chilling tolerance reported to occur with ripening and solar exposure.

scholarly journals Biogenesis of mitochondria*. The effects of altered membrane lipid composition on cation transport by mitochondria of Saccharomyces cerevisiae

1973 ◽  
Vol 134 (4) ◽  
pp. 949-957 ◽  
Author(s):  
J. M. Haslam ◽  
T. W. Spithill ◽  
Anthony W. Linnane ◽  
J. B. Chappell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Oxidative Phosphorylation ◽  
Free Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Cation Transport ◽  
Lipid Phase ◽  
Yeast Mitochondria ◽  
Passive Permeability

1. The fatty acid composition of the membrane lipids of a fatty acid desaturase mutant of Saccharomyces cerevisiae was manipulated by growing the organism in a medium containing defined fatty acid supplements. 2. Mitochondria were obtained whose fatty acids contain between 20% and 80% unsaturated fatty acids. 3. Mitochondria with high proportions of unsaturated fatty acids in their lipids have coupled oxidative phosphorylation with normal P/O ratios, accumulate K+ ions in the presence of valinomycin and an energy source, and eject protons in an energy-dependent fashion. 4. If the unsaturated fatty acid content of the mitochondrial fatty acids is lowered to 20%, the mitochondria simultaneously lose active cation transport and the ability to couple phosphorylation to respiration. 5. The loss of energy-linked reactions is accompanied by an increased passive permeability of the mitochondria to protons. 6. Free fatty acids uncouple oxidative phosphorylation in yeast mitochondria and the effect is reversed by bovine serum albumin. 7. The free fatty acid contents of yeast mitochondria are unaffected by depletion of unsaturated fatty acids, and free fatty acids are not responsible for the uncoupling of oxidative phosphorylation in organelles depleted in unsaturated fatty acids. 8. It is suggested that the loss of energy-linked reactions in yeast mitochondria that are depleted in unsaturated fatty acids is a consequence of the increased passive permeability to protons, and is caused by a change in the physical properties of the lipid phase of the inner mitochondrial membrane.

scholarly journals Fatty acid desaturation and microsomal lipid fatty acid composition in experimental hypothyroidism

1982 ◽  
Vol 207 (1) ◽  
pp. 29-35 ◽  
Author(s):  
F H Faas ◽  
W J Carter
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Desaturase Activity ◽  
Unsaturated Fatty Acids ◽  
Lipid Fatty Acid ◽  
Rate Controlling Step ◽  
Delta 6 Desaturase ◽  
Lipid Fatty Acid Composition

We have studied the influence of experimental hypothyroidism in the rat on the synthesis of unsaturated fatty acids and on liver microsomal lipid fatty acid composition. Hypothyroid rats demonstrated an 80% decrease in delta 9 (stearate) desaturation and a 43% decrease in delta 6 (linoleate) desaturation. Liver microsomal fatty acid composition was altered in the hypothyroid animals with a significantly decreased proportion of arachidonate and increased proportions of linoleate, eicosa-8,11,14-trienoate, eicosapentaenoate and docosahexaenoate. The bulk of these changes occurred in both of the two major phospholipid components, phosphatidylcholine and phosphatidylethanolamine. All of the changes were corrected by treatment of the hypothyroid rat with 25 micrograms of tri-iodothyronine/100 g body wt. twice daily. The diminished delta 9 desaturation did not lead to any changes in fatty acid composition. The increased linoleate and decreased arachidonate levels may be due to the diminished delta 6 desaturase activity, the rate-controlling step in the conversion of linoleate into arachidonate. The increases in the proportions of the other polyunsaturated fatty acid components cannot be explained by changes in the synthesis of unsaturated fatty acids, but are probably due to diminished utilization of these fatty acids.

scholarly journals The fabM Gene Product of Streptococcus mutans Is Responsible for the Synthesis of Monounsaturated Fatty Acids and Is Necessary for Survival at Low pH

2004 ◽  
Vol 186 (13) ◽  
pp. 4152-4158 ◽  
Author(s):  
Elizabeth M. Fozo ◽  
Robert G. Quivey
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Streptococcus Mutans ◽  
Unsaturated Fatty Acids ◽  
Fatty Acid Biosynthesis ◽  
Monounsaturated Fatty Acids ◽  
Low Ph ◽  
Membrane Composition ◽  
Appl Environ ◽  
Altered Glucose

ABSTRACT Previously, it has been demonstrated that the membrane fatty acid composition of Streptococcus mutans is affected by growth pH (E. M. Fozo and R. G. Quivey, Jr., Appl. Environ. Microbiol. 70:929-936, 2004; R. G. Quivey, Jr., R. Faustoferri, K. Monahan, and R. Marquis, FEMS Microbiol. Lett. 189:89-92, 2000). Specifically, the proportion of monounsaturated fatty acids increases when the organism is grown in acidic environments; if the shift to increased monounsaturated fatty acids is blocked by the addition of a fatty acid biosynthesis inhibitor, the organism is rendered more acid sensitive (E. M. Fozo and R. G. Quivey, Jr., Appl. Environ. Microbiol. 70:929-936, 2004). Recently, work with Streptococcus pneumoniae has identified a novel enzyme, FabM, responsible for the production of monounsaturated fatty acids (H. Marrakchi, K. H. Choi, and C. O. Rock, J. Biol. Chem. 277:44809-44816, 2002). Using the published S. pneumoniae sequence, a putative FabM was identified in the S. mutans strain UA159. We generated a fabM strain that does not produce unsaturated fatty acids as determined by gas chromatography of fatty acid methyl esters. The mutant strain was extremely sensitive to low pH in comparison to the wild type; however, the acid-sensitive phenotype was relieved by growth in the presence of long-chain monounsaturated fatty acids or through genetic complementation. The strain exhibited reduced glycolytic capability and altered glucose-PTS activity. In addition, the altered membrane composition was more impermeable to protons and did not maintain a normal ΔpH. The results suggest that altered membrane composition can significantly affect the acid survival capabilities, as well as several enzymatic activities, of S. mutans.

scholarly journals Expressing a Cytosolic Pyruvate Dehydrogenase Complex to Increase Free Fatty Acid Production in Saccharomyces Cerevisiae

2020 ◽  
Author(s):  
Yiming Zhang ◽  
Mo Su ◽  
Ning Qin ◽  
Jens Nielsen ◽  
Zihe Liu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Pyruvate Dehydrogenase ◽  
Unsaturated Fatty Acids ◽  
Pyruvate Dehydrogenase Complex ◽  
Cell Factory ◽  
Acetyl Coa ◽  
Fatty Acid Production

Abstract Background Saccharomyces cerevisiae is being exploited as a cell factory to produce fatty acids and their derivatives as biofuels. Previous studies found that both precursor supply and fatty acid metabolism deregulation are essential for enhanced fatty acid synthesis. A bacterial pyruvate dehydrogenase (PDH) complex expressed in the yeast cytosol was reported to enable production of cytosolic acetyl-CoA with lower energy cost and no toxic intermediate. Results Overexpression of the PDH complex significantly increased cell growth, ethanol consumption and reduced glycerol accumulation. Furthermore, to optimize the redox imbalance in production of fatty acids from glucose, two endogenous NAD+-dependent glycerol-3-phosphate dehydrogenases were deleted, and a heterologous NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase was introduced. The final strain with engineering of precursor and co-factor metabolism could produce 840.5 mg/L free fatty acid in shake flask, which was 83.2% higher than the control strain. Profile analysis of free fatty acid suggested the cytosolic PDH complex mainly resulted in the increases of unsaturated fatty acids (C16:1 and C18:1). Conclusions We demonstrated that cytosolic PDH pathway enabled more efficient acetyl-CoA provision with the lower ATP cost, and improved FFA production. Together with engineering of the redox factor rebalance, the cytosolic PDH pathway could achieve high level of FFA production at similar levels of other best acetyl-CoA producing pathways.

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