scholarly journals Glucose Metabolism in Lactococcus lactis MG1363 under Different Aeration Conditions: Requirement of Acetate To Sustain Growth under Microaerobic Conditions

2003 ◽  
Vol 69 (6) ◽  
pp. 3462-3468 ◽  
Author(s):  
Mikkel Nordkvist ◽  
Niels Bang Siemsen Jensen ◽  
John Villadsen
Keyword(s):  
Lactococcus Lactis ◽  
Specific Growth ◽  
Acid Synthesis ◽  
Product Formation ◽  
Defined Medium ◽  
Acetyl Coa ◽  
Dissolved Oxygen Tension ◽  
Batch Cultures ◽  
Aeration Conditions ◽  
Microaerobic Conditions

ABSTRACT Lactococcus lactis subsp. lactis MG1363 was grown in batch cultures on a defined medium with glucose as the energy source under different aeration conditions, namely, anaerobic conditions, aerobic conditions, and microaerobic conditions with a dissolved oxygen tension of 5% (when saturation with air was used as the reference). The maximum specific growth rate was high (0.78 to 0.91 h−1) under all aeration conditions but decreased with increasing aeration, and more than 90% of the glucose was converted to lactate. However, a shift in by-product formation was observed. Increasing aeration resulted in acetate, CO2, and acetoin replacing formate and ethanol as end products. Under microaerobic conditions, growth came to a gradual halt, although more than 60% of the glucose was still left. A decline in growth was not observed during microaerobic cultivation when acetate was added to the medium. We hypothesize that the decline in growth was due to a lack of acetyl coenzyme A (acetyl-CoA) needed for fatty acid synthesis since acetyl-CoA can be synthesized from acetate by means of acetate kinase and phosphotransacetylase activities.

scholarly journals The Joint Effect of pH Gradient and Glucose Feeding on the Growth Kinetics of Lactococcus lactis CECT 539 in Glucose-Limited Fed-Batch Cultures

2019 ◽  
Vol 68 (2) ◽  
pp. 269-280
Author(s):  
MÓNICA COSTAS MALVIDO ◽  
ELISA ALONSO GONZÁLEZ ◽  
RICARDO J. BENDAÑA JÁCOME ◽  
NELSON PÉREZ GUERRA
Keyword(s):  
Lactococcus Lactis ◽  
Viable Cell ◽  
Product Formation ◽  
Ph Gradient ◽  
Feeding Strategies ◽  
Fed Batch ◽  
Batch Cultures ◽  
Cell Counts ◽  
First Time ◽  
Kinetics Of

Two glucose-limited realkalized fed-batch cultures of Lactococcus lactis CECT 539 were carried out in a diluted whey medium (DW) using two different feeding media. The cultures were fed a mixture of a 400 g/l concentrated lactose and a concentrated mussel processing waste (CMPW, 101.72 g glucose/l) medium (fermentation I) or a CMPW medium supplemented with glucose and KH2PO4 up to concentrations of 400 g glucose/l and 3.21 g total phosphorus/l, respectively (fermentation II). For an accurate description and a better understanding of the kinetics of both cultures, the growth and product formation by L. lactis CECT 539 were both modelled, for the first time, as a function of the amounts of glucose (G) added and the pH gradient (VpH) generated in every realkalization and feeding cycle, by using an empirical polynomial model. With this modeling procedure, the kinetics of biomass, viable cell counts, nisin, lactic acid, acetic acid and butane-2,3-diol production in both cultures were successfully described (R2 values > 0.970) and interpreted for the first time. In addition, the optimum VpH and G values for each product were accurately calculated in the two realkalized fed-batch cultures. This approach appears to be useful for designing feeding strategies to enhance the productions of biomass, bacteriocin, and metabolites by the nisin-producing strain in wastes from the food industry.

The effect of energy and nitrogen supply pattern on rumen bacterial growthin vitro

1991 ◽  
Vol 53 (2) ◽  
pp. 165-175 ◽  
Author(s):  
P. H. Henning ◽  
D. G. Steyn ◽  
H. H. Meissner
Keyword(s):  
Bacterial Growth ◽  
Specific Growth ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Batch Cultures ◽  
Time Zero ◽  
N Supply ◽  
Pulse Dose ◽  
Supply Pattern ◽  
Glucose Supply

AbstractThe effect of energy and nitrogen (N) supply pattern on rumen bacterial growth was investigated in vitro. In experiment 1, glucose was was fed to batch cultures of mixed rumen bacteria according to three patterns namely a pulse dose at time zero (P); even increments at 0·5-h intervals (G) or an intermediate pattern (I), whilst N was supplied in excess. In experiment 2, glucose and N (not in excess) were fed to batch cultures according to four patterns namely glucose and N as pulse doses at time zero, (EPNP); glucose as a pulse dose at time zero and N in 24 even increments at 0·5-h intervals (EPNG); glucose in 24 even increments at 0·5-h intervals and N as a pulse dose at time zero (EGNP) or both glucose and N in 24 even increments at 0·5-h intervals (EGNG). Fermentaton was studied over a 12-h period for both experiments.In experiment 1, bacterial growth efficiency and specific growth rate (39·8,35·5 and 29·9 (g bacterial dry matter (DM) per mol glucose utilized) and 0·33, 0·27 and 0·20 (fraction per h) for treatments P, I, and G respectively) differed significantly between glucose supply patterns. In experiment 2, bacterial growth efficiency and specific growth rate (33·8, 34·7, 25·9 and 22·5 (g baterial DM per mol glucose) and 0·21, 0·18, 0·14 and 0·13 (fraction per h) for treatments EPNP, EPNG, EGNP and EGNG respectively) differed significantly only between glucose supply patterns.It is concluded that the pattern according to which a given amount of energy becomes available affects bacterial growth efficiency, with the fastest supply rate giving the highest efficiency and that, within accepted levels of N supply, synchronization between energy and N availability may be of less importance to bacterial growth efficiency than the energy supply pattern.

scholarly journals HFA1 Encoding an Organelle-specific Acetyl-CoA Carboxylase Controls Mitochondrial Fatty Acid Synthesis inSaccharomyces cerevisiae

2004 ◽  
Vol 279 (21) ◽  
pp. 21779-21786 ◽  
Author(s):  
Ursula Hoja ◽  
Sandra Marthol ◽  
Jörg Hofmann ◽  
Sabine Stegner ◽  
Rainer Schulz ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Mitochondrial Fatty Acid

scholarly journals Characterization of the Role of para-Aminobenzoic Acid Biosynthesis in Folate Production by Lactococcus lactis

2007 ◽  
Vol 73 (8) ◽  
pp. 2673-2681 ◽  
Author(s):  
Arno Wegkamp ◽  
Wietske van Oorschot ◽  
Willem M. de Vos ◽  
Eddy J. Smid
Keyword(s):  
Gene Cluster ◽  
Lactococcus Lactis ◽  
Gene Clusters ◽  
Defined Medium ◽  
Biosynthesis Pathway ◽  
Chemically Defined Medium ◽  
Aminobenzoic Acid ◽  
Biosynthesis Gene Cluster ◽  
Gene Coding ◽  
Aba Biosynthesis

ABSTRACT The pab genes for para-aminobenzoic acid (pABA) biosynthesis in Lactococcus lactis were identified and characterized. In L. lactis NZ9000, only two of the three genes needed for pABA production were initially found. No gene coding for 4-amino-4-deoxychorismate lyase (pabC) was initially annotated, but detailed analysis revealed that pabC was fused with the 3′ end of the gene coding for chorismate synthetase component II (pabB). Therefore, we hypothesize that all three enzyme activities needed for pABA production are present in L. lactis, allowing for the production of pABA. Indeed, the overexpression of the pABA gene cluster in L. lactis resulted in elevated pABA pools, demonstrating that the genes are involved in the biosynthesis of pABA. Moreover, a pABA knockout (KO) strain lacking pabA and pabB C was constructed and shown to be unable to produce folate when cultivated in the absence of pABA. This KO strain was unable to grow in chemically defined medium lacking glycine, serine, nucleobases/nucleosides, and pABA. The addition of the purine guanine, adenine, xanthine, or inosine restored growth but not the production of folate. This suggests that, in the presence of purines, folate is not essential for the growth of L. lactis. It also shows that folate is not strictly required for the pyrimidine biosynthesis pathway. L. lactis strain NZ7024, overexpressing both the folate and pABA gene clusters, was found to produce 2.7 mg of folate/liter per optical density unit at 600 nm when the strain was grown on chemically defined medium without pABA. This is in sharp contrast to L. lactis strains overexpressing only one of the two gene clusters. Therefore, we conclude that elevated folate levels can be obtained only by the overexpression of folate combined with the overexpression of the pABA biosynthesis gene cluster, suggesting the need for a balanced carbon flux through the folate and pABA biosynthesis pathway in the wild-type strain.

scholarly journals Regulation of fatty acid synthesis and malonyl-CoA content in mouse brown adipose tissue in response to cold-exposure, starvation or re-feeding

1987 ◽  
Vol 243 (2) ◽  
pp. 437-442 ◽  
Author(s):  
M G Buckley ◽  
E A Rath
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fatty Acid Synthesis ◽  
Cold Exposure ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Malonyl Coa ◽  
Brown Adipose

1. The effect of nutritional status on fatty acid synthesis in brown adipose tissue was compared with the effect of cold-exposure. Fatty acid synthesis was measured in vivo by 3H2O incorporation into tissue lipids. The activities of acetyl-CoA carboxylase and fatty acid synthetase and the tissue concentrations of malonyl-CoA and citrate were assayed. 2. In brown adipose tissue of control mice, the tissue content of malonyl-CoA was 13 nmol/g wet wt., higher than values reported in other tissues. From the total tissue water content, the minimum possible concentration was estimated to be 30 microM 3. There were parallel changes in fatty acid synthesis, malonyl-CoA content and acetyl-CoA carboxylase activity in response to starvation and re-feeding. 4. There was no correlation between measured rates of fatty acid synthesis and malonyl-CoA content and acetyl-CoA carboxylase activity in acute cold-exposure. The results suggest there is simultaneous fatty acid synthesis and oxidation in brown adipose tissue of cold-exposed mice. This is probably effected not by decreases in the malonyl-CoA content, but by increases in the concentration of free long-chain fatty acyl-CoA or enhanced peroxisomal oxidation, allowing shorter-chain fatty acids to enter the mitochondria independent of carnitine acyltransferase (overt form) activity.

scholarly journals ChREBP-Mediated Regulation of Lipid Metabolism: Involvement of the Gut Microbiota, Liver, and Adipose Tissue

2020 ◽  
Vol 11 ◽  
Author(s):  
Katsumi Iizuka ◽  
Ken Takao ◽  
Daisuke Yabe
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Lipid Metabolism ◽  
Gut Microbiota ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Acid Synthesis ◽  
Whole Body ◽  
Acetyl Coa ◽  
Alcoholic Fatty Liver

Carbohydrate response element-binding protein (ChREBP) plays an important role in the development of type 2 diabetes, dyslipidemia, and non-alcoholic fatty liver disease, as well as tumorigenesis. ChREBP is highly expressed in lipogenic organs, such as liver, intestine, and adipose tissue, in which it regulates the production of acetyl CoA from glucose by inducing Pklr and Acyl expression. It has recently been demonstrated that ChREBP plays a role in the conversion of gut microbiota-derived acetate to acetyl CoA by activating its target gene, Acss2, in the liver. ChREBP regulates fatty acid synthesis, elongation, and desaturation by inducing Acc1 and Fasn, elongation of long-chain fatty acids family member 6 (encoded by Elovl6), and Scd1 expression, respectively. ChREBP also regulates the formation of very low-density lipoprotein by inducing the expression of Mtp. Furthermore, it plays a crucial role in peripheral lipid metabolism by inducing Fgf21 expression, as well as that of Angptl3 and Angptl8, which are known to reduce peripheral lipoprotein lipase activity. In addition, ChREBP is involved in the production of palmitic-acid-5-hydroxystearic-acid, which increases insulin sensitivity in adipose tissue. Curiously, ChREBP is indirectly involved in fatty acid β-oxidation and subsequent ketogenesis. Thus, ChREBP regulates whole-body lipid metabolism by controlling the transcription of lipogenic enzymes and liver-derived cytokines.

scholarly journals Quantitative Physiology of Saccharomyces cerevisiae at Near-Zero Specific Growth Rates

2009 ◽  
Vol 75 (17) ◽  
pp. 5607-5614 ◽  
Author(s):  
L�onie G. M. Boender ◽  
Erik A. F. de Hulster ◽  
Antonius J. A. van Maris ◽  
Pascale A. S. Daran-Lapujade ◽  
Jack T. Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rates ◽  
Specific Growth ◽  
Biomass Concentration ◽  
Product Formation ◽  
Energy Requirements ◽  
Maintenance Energy ◽  
Key Issues ◽  
Complete Cell ◽  
Specific Growth Rates

ABSTRACT Growth at near-zero specific growth rates is a largely unexplored area of yeast physiology. To investigate the physiology of Saccharomyces cerevisiae under these conditions, the effluent removal pipe of anaerobic, glucose-limited chemostat culture (dilution rate, 0.025 h−1) was fitted with a 0.22-μm-pore-size polypropylene filter unit. This setup enabled prolonged cultivation with complete cell retention. After 22 days of cultivation, specific growth rates had decreased below 0.001 h−1 (doubling time of >700 h). Over this period, viability of the retentostat cultures decreased to ca. 80%. The viable biomass concentration in the retentostats could be accurately predicted by a maintenance coefficient of 0.50 mmol of glucose g−1 of biomass h−1 calculated from anaerobic, glucose-limited chemostat cultures grown at dilution rates of 0.025 to 0.20 h−1. This indicated that, in contrast to the situation in several prokaryotes, maintenance energy requirements in S. cerevisiae do not substantially change at near-zero specific growth rates. After 22 days of retentostat cultivation, glucose metabolism was predominantly geared toward alcoholic fermentation to meet maintenance energy requirements. The strict correlation between glycerol production and biomass formation observed at higher specific growth rates was not maintained at the near-zero growth rates reached in the retentostat cultures. In addition to glycerol, the organic acids acetate, d-lactate, and succinate were produced at low rates during prolonged retentostat cultivation. This study identifies robustness and by-product formation as key issues in attempts to uncouple growth and product formation in S. cerevisiae.

Fatty acid synthesis: from CO2 to functional genomics

2000 ◽  
Vol 28 (6) ◽  
pp. 567-574 ◽  
Author(s):  
J. Ohlrogge ◽  
M. Pollard ◽  
X. Bao ◽  
M. Focke ◽  
T. Girke ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Regulatory Networks ◽  
Fatty Acid Synthase ◽  
Expression Patterns ◽  
Acid Synthesis ◽  
Acetyl Coa ◽  
Specific Expression ◽  
Direct Production

For over 25 years there has been uncertainty over the pathway from CO2, to acetyl-CoA in chloroplasts. On the one hand, free acetate is the most effective substrate for fatty acid synthesis by isolated chloroplasts, and free acetate concentrations reported in leaf tissue (0.1–1 mM) appear adequate to saturate fatty acid synthase. On the other hand, a clear mechanism to generate sufficient free acetate for fatty acid synthesis is not established and direct production of acetyl-CoA from pyruvate by a plastid pyruvate dehydrogenase seems a more simple and direct path. We have re-examined this question and attempted to distinguish between the alternatives. The kinetics of 13CO2 and 14CO2 movement into fatty acids and the absolute rate of fatty acid synthesis in leaves was determined in light and dark. Because administered 14C appears in fatty acids within < 2–3 min our results are inconsistent with a large pool of free acetate as an intermediate in leaf fatty acid synthesis. In addition, these studies provide an estimate of the turnover rate of fatty acid in leaves. Studies similar to the above are more complex in seeds, and some questions about the regulation of plant lipid metabolism seem difficult to solve using conventional biochemical or molecular approaches. For example, we have little understanding of why or how some seeds produce >50%, oil whereas other seeds store largely carbohydrate or protein. Major control over complex plant biochemical pathways may only become possible by understanding regulatory networks which provide ‘global’ control over these pathways. To begin to discover such networks and provide a broad analysis of gene expression in developing oilseeds, we have produced micro-arrays that display approx. 5000 seed-expressed Arabidopsis genes. Sensitivity of the arrays was 1–2 copies of mRNA/cell. The arrays have been hybridized with probes derived from seeds, leaves and roots, and analysis of expression ratios between the different tissues has allowed the tissue-specific expression patterns of many hundreds of genes to be described for the first time. Approx. 10% of the genes were expressed at ratios ≥ 10-fold higher in seeds than in leaves or roots. Included in this list are a large number of proteins of unknown function, and potential regulatory factors such as protein kinases, phosphatases and transcription factors. The arrays were also found to be useful for analysis of Brassica seeds.

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