20 assays (manual) / 200 assays (microplate) / 270 assays (auto-analyser)
Prices exclude VAT
Available for shipping
|20 assays (manual) / 200 assays (microplate) / 270 assays (auto-analyser)
| Short term stability: 2-8oC,
Long term stability: See individual component labels
|> 2 years under recommended storage conditions
|Succinic Acid (Succinate)
|Spectrophotometer, Microplate, Auto-analyser
|0.8 to 40 µg of succinic acid per assay
|Limit of Detection:
|Reaction Time (min):
|~ 6 min
|Wine, fruit and vegetables, soy sauce, cheese, egg, egg products and other materials (e.g. biological cultures, samples, etc.).
|Methods based on this principle have been accepted by EEC and EN
The Succinic Acid (Succinate) assay kit is suitable for the specific assay of succinic acid in wine, cheese, eggs, sauce and other food products.
Succinic acid (or succinate) is found in all plant and animal materials as a result of the central metabolic role played by this dicarboxylic acid in the Citric Acid Cycle. Succinic acid concentrations are monitored in the manufacture of numerous foodstuffs and beverages, including wine, soy sauce, soy bean flour, fruit juice and dairy products (e.g. cheese).
Note for Content: The number of manual tests per kit can be doubled if all volumes are halved. This can be readily accommodated using the MegaQuantTM Wave Spectrophotometer (D-MQWAVE).
Browse all of our organic acid assay kits.
- Extended cofactors stability. Dissolved cofactors stable for > 1 year at 4oC.
- Very competitive price (cost per test)
- All reagents stable for > 2 years as supplied
- Very rapid reaction (even at room temperature)
- Mega-Calc™ software tool is available from our website for hassle-free raw data processing
- Standard included
- Suitable for manual, microplate and auto-analyser formats
Megazyme “advanced” wine test kits general characteristics and validation.
Charnock, S. J., McCleary, B. V., Daverede, C. & Gallant, P. (2006). Reveue des Oenologues, 120, 1-5.
Many of the enzymatic test kits are official methods of prestigious organisations such as the Association of Official Analytical Chemicals (AOAC) and the American Association of Cereal Chemists (AACC) in response to the interest from oenologists. Megazyme decided to use its long history of enzymatic bio-analysis to make a significant contribution to the wine industry, by the development of a range of advanced enzymatic test kits. This task has now been successfully completed through the strategic and comprehensive process of identifying limitations of existing enzymatic bio-analysis test kits where they occurred, and then using advanced techniques, such as molecular biology (photo 1), to rapidly overcome them. Novel test kits have also been developed for analytes of emerging interest to the oenologist, such as yeast available nitrogen (YAN; see pages 2-3 of issue 117 article), or where previously enzymes were simply either not available, or were too expensive to employ, such as for D-mannitol analysis.Hide Abstract
Grape and wine analysis: Oenologists to exploit advanced test kits.
Charnock, S. C. & McCleary, B. V. (2005). Revue des Enology, 117, 1-5.
It is without doubt that testing plays a pivotal role throughout the whole of the vinification process. To produce the best possible quality wine and to minimise process problems such as “stuck” fermentation or troublesome infections, it is now recognised that if possible testing should begin prior to harvesting of the grapes and continue through to bottling. Traditional methods of wine analysis are often expensive, time consuming, require either elaborate equipment or specialist expertise and frequently lack accuracy. However, enzymatic bio-analysis enables the accurate measurement of the vast majority of analytes of interest to the wine maker, using just one piece of apparatus, the spectrophotometer (see previous issue No. 116 for a detailed technical review). Grape juice and wine are amenable to enzymatic testing as being liquids they are homogenous, easy to manipulate, and can generally be analysed without any sample preparation.Hide Abstract
The phenotype and genotype of fermentative prokaryotes.
Hackmann, T. J. & Zhang, B. (2023). Science Advances, 9(39), eadg8687.
Fermentation is a type of metabolism pervasive in oxygen-deprived environments. Despite its importance, we know little about the range and traits of organisms that carry out this metabolism. Our study addresses this gap with a comprehensive analysis of the phenotype and genotype of fermentative prokaryotes. We assembled a dataset with phenotypic records of 8350 organisms plus 4355 genomes and 13.6 million genes. Our analysis reveals fermentation is both widespread (in ~30% of prokaryotes) and complex (forming ~300 combinations of metabolites). Furthermore, it points to previously uncharacterized proteins involved in this metabolism. Previous studies suggest that metabolic pathways for fermentation are well understood, but metabolic models built in our study show gaps in our knowledge. This study demonstrates the complexity of fermentation while showing that there is still much to learn about this metabolism. All resources in our study can be explored by the scientific community with an online, interactive tool.Hide Abstract
Gastrodin alleviates NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in trigeminal ganglion.
Ma, C., Zhu, C., Zhang, Y., Yu, M., Song, Y., Chong, Y., Yang, Y., Zhu, C., Jiang, Y., Wang, C., Cheng, S., Jia, K., Yu, G., Li, J. & Tang, Z. (2024). Phytomedicine, 125, 155266.
Background: Increasing evidence highlights the involvement of metabolic disorder and calcium influx mediated by transient receptor potential channels in migraine; however, the relationship between these factors in the pathophysiology of migraine remains unknown. Gastrodin is the major component of the traditional Chinese medicine Tianma, which is extensively used in migraine therapy. Purpose: Our work aimed to explore the analgesic action of gastrodin and its regulatory mechanisms from a metabolic perspective. Methods/results: After being treated with gastrodin, the mice were given nitroglycerin (NTG) to induce migraine. Gastrodin treatment significantly raised the threshold of sensitivity in response to both mechanical and thermal stimulus evidenced by von Frey and hot plate tests, respectively, and decreased total contact numbers in orofacial operant behavioral assessment. We found that the expression of transient receptor potential melastatin 2 (TRPM2) channel was increased in the trigeminal ganglion (TG) of NTG-induced mice, resulting in a sustained Ca2+ influx to trigger migraine pain. The content of succinate, a metabolic biomarker, was elevated in blood samples of migraineurs, as well as in the serum and TG tissue from NTG-induced migraine mice. Calcium imaging assay indicated that succinate insult elevated TRPM2-mediated calcium flux signal in TG neurons. Mechanistically, accumulated succinate upregulated hypoxia inducible factor-1α (HIF-1α) expression and promoted its translocation into nucleus, where HIF-1α enhanced TRPM2 expression through transcriptional induction in TG neurons, evidenced by luciferase reporter measurement. Gastrodin treatment inhibited TRPM2 expression and TRPM2-dependent Ca2+ influx by attenuating succinate accumulation and downstream HIF-1α signaling, and thereby exhibited analgesic effect. Conclusion: This work revealed that succinate was a critical metabolic signaling molecule and the key mediator of migraine pain through triggering TRPM2-mediated calcium overload. Gastrodin alleviated NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in TG neurons. These findings uncovered the anti-migraine effect of gastrodin and its regulatory mechanisms from a metabolic perspective and provided a novel theoretical basis for the analgesic action of gastrodin.Hide Abstract
Bioconversion of cellulose into bisabolene using Ruminococcus flavefaciens and Rhodosporidium toruloides.
Walls, L. E., Otoupal, P., Ledesma-Amaro, R., Velasquez-Orta, S. B., Gladden, J. M. & Rios-Solis, L. (2022). Bioresource Technology, 368, 128216.
In this study, organic acids were demonstrated as a promising carbon source for bisabolene production by the non-conventional yeast, Rhodosporidium toruloides, at microscale with a maximum titre of 1055 ± 7 mg/L. A 125-fold scale-up of the optimal process, enhanced bisabolene titres 2.5-fold to 2606 mg/L. Implementation of a pH controlled organic acid feeding strategy at this scale lead to a further threefold improvement in bisabolene titre to 7758 mg/L, the highest reported microbial titre. Finally, a proof-of-concept sequential bioreactor approach was investigated. Firstly, the cellulolytic bacterium Ruminococcus flavefaciens was employed to ferment cellulose, yielding 4.2 g/L of organic acids. R. toruloides was subsequently cultivated in the resulting supernatant, producing 318 ± 22 mg/L of bisabolene. This highlights the feasibility of a sequential bioprocess for the bioconversion of cellulose, into biojet fuel candidates. Future work will focus on enhancing organic acid yields and the use of real lignocellulosic feedstocks to further enhance bisabolene production.Hide Abstract
PEG35 and Glutathione Improve Mitochondrial Function and Reduce Oxidative Stress in Cold Fatty Liver Graft Preservation.
Bardallo, R. G., Folch-Puy, E., Roselló-Catafau, J., Panisello-Rosello, A. & Carbonell, T. (2022). Antioxidants, 11(1), 158.
The need to meet the demand for transplants entails the use of steatotic livers, more vulnerable to ischemia-reperfusion (IR) injury. Therefore, finding the optimal composition of static cold storage (SCS) preservation solutions is crucial. Given that ROS regulation is a therapeutic strategy for liver IR injury, we have added increasing concentrations of PEG35 and glutathione (GSH) to the preservation solutions (IGL-1 and IGL-2) and evaluated the possible protection against energy depletion and oxidative stress. Fatty livers from obese Zücker rats were isolated and randomly distributed in the control (Sham) preserved (24 h at 4°C) in IGL-0 (without PEG35 and 3 mmol/L GSH), IGL-1 (1 g/L PEG35, and 3 mmol/L GSH), and IGL-2 (5 g/L PEG35 and 9 mmol/L GSH). Energy metabolites (ATP and succinate) and the expression of mitochondrial oxidative phosphorylation complexes (OXPHOS) were determined. Mitochondrial carrier uncoupling protein 2 (UCP2), PTEN-induced kinase 1 (PINK1), nuclear factor-erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the inflammasome (NLRP3) expressions were analyzed. As biomarkers of oxidative stress, protein oxidation (AOPP) and carbonylation (DNP derivatives), and lipid peroxidation (malondialdehyde (MDA)-thiobarbituric acid (TBA) adducts) were measured. In addition, the reduced and oxidized glutathione (GSH and GSSG) and enzymatic (Cu-Zn superoxide dismutase (SOD), CAT, GSH S-T, GSH-Px, and GSH-R) antioxidant capacities were determined. Our results showed that the cold preservation of fatty liver graft depleted ATP, accumulated succinate and increased oxidative stress. In contrast, the preservation with IGL-2 solution maintained ATP production, decreased succinate levels and increased OXPHOS complexes I and II, UCP2, and PINK-1 expression, therefore maintaining mitochondrial integrity. IGL-2 also protected against oxidative stress by increasing Nrf2 and HO-1 expression and GSH levels. Therefore, the presence of PEG35 in storage solutions may be a valuable option as an antioxidant agent for organ preservation in clinical transplantation.Hide Abstract
Modulation of a defined community of Oenococcus oeni strains by Torulaspora delbrueckii and its impact on malolactic fermentation.
Balmaseda, A., Rozès, N., Bordons, A. & Reguant, C. (2021). Australian Journal of Grape and Wine Research, In Press.
Background and Aims: Torulaspora delbrueckii is being used increasingly as a starter for alcoholic fermentation (AF) because of its chemical modulation of wine. Previous studies on this yeast in a natural must have shown a different Oenococcus oeni population by the end of MLF. In this study we aim to evaluate this aspect in a defined O. oeni strain consortium in a sterile grape must during winemaking. Methods and Results: Before commencing AF with either S. cerevisiae or both T. delbrueckii and S. cerevisiae, the must was inoculated with a defined population of O. oeni strains. The use of T. delbrueckii determined the bacterial population at the end of MLF. Also, the inoculation of a selected strain after AF produced wines with different chemical composition to those fermented with the initial bacterial community. Conclusions: Different yeast inoculation strategies modulate the O. oeni population, and this has an impact on the chemical composition of the wines. Moreover, the inoculation of a small O. oeni population in must leads to a process similar to spontaneous MLF. Significance of the Study: Torulaspora delbrueckii can be used as a tool to modulate the O. oeni population and enhance the aromas related to MLF.Hide Abstract
Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions.
Ciosek, A., Fulara, K., Hrabia, O., Satora, P. & Poreda, A. (2020). Biomolecules, 10(12), 1599.
The bioavailability of minerals, such as zinc and magnesium, has a significant impact on the fermentation process. These metal ions are known to influence the growth and metabolic activity of yeast, but there are few reports on their effects on lactic acid bacteria (LAB) metabolism during sour brewing. This study aimed to evaluate the influence of magnesium and zinc ions on the metabolism of Lactobacillus brevis WLP672 during the fermentation of brewers’ wort. We carried out lactic acid fermentations using wort with different mineral compositions: without supplementation; supplemented with magnesium at 60 mg/L and 120 mg/L; and supplemented with zinc at 0.4 mg/L and 2 mg/L. The concentration of organic acids, pH of the wort and carbohydrate use was determined during fermentation, while aroma compounds, real extract and ethanol were measured after the mixed fermentation. The addition of magnesium ions resulted in the pH of the fermenting wort decreasing more quickly, an increase in the level of L-lactic acid (after 48 h of fermentation) and increased concentrations of some volatile compounds. While zinc supplementation had a negative impact on the L. brevis strain, resulting in a decrease in the L-lactic acid content and a higher pH in the beer. We conclude that zinc supplementation is not recommended in sour beer production using L. brevis WLP672.Hide Abstract
Succinate Supplement Elicited “Pseudohypoxia” Condition to Promote Proliferation, Migration, and Osteogenesis of Periodontal Ligament Cells.
Mao, H., Yang, A., Zhao, Y., Lei, L. & Li, H. (2020). Stem Cells International, 2020, 2016809.
Most mesenchymal stem cells reside in a niche of low oxygen tension. Iron-chelating agents such as CoCl2 and deferoxamine have been utilized to mimic hypoxia and promote cell growth. The purpose of the present study was to explore whether a supplement of succinate, a natural metabolite of the tricarboxylic acid (TCA) cycle, can mimic hypoxia condition to promote human periodontal ligament cells (hPDLCs). Culturing hPDLCs in hypoxia condition promoted cell proliferation, migration, and osteogenic differentiation; moreover, hypoxia shifted cell metabolism from oxidative phosphorylation to glycolysis with accumulation of succinate in the cytosol and its release into culture supernatants. The succinate supplement enhanced hPDLC proliferation, migration, and osteogenesis with decreased succinate dehydrogenase (SDH) expression and activity, as well as increased hexokinase 2 (HK2) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), suggesting metabolic reprogramming from oxidative phosphorylation to glycolysis in a normal oxygen condition. The succinate supplement in cell cultures promoted intracellular succinate accumulation while stabilizing hypoxia inducible factor-1α (HIF-1α), leading to a state of pseudohypoxia. Moreover, we demonstrate that hypoxia-induced proliferation was G-protein-coupled receptor 91- (GPR91-) dependent, while exogenous succinate-elicited proliferation involved the GPR91-dependent and GPR91-independent pathway. In conclusion, the succinate supplement altered cell metabolism in hPDLCs, induced a pseudohypoxia condition, and enhanced proliferation, migration, and osteogenesis of mesenchymal stem cells in vitro.Hide Abstract
Exposure to amoxicillin in early life is associated with changes in gut microbiota and reduction in blood pressure: findings from a study on rat dams and offspring.
Galla, S., Chakraborty, S., Cheng, X., Yeo, J. Y., Mell, B., Chiu, N., Wenceslau, C. F., Vijay‐Kumar, M. & Joe, B. (2020). Journal of the American Heart Association, 9(2), e014373.
Background: Pediatric hypertension is recognized as an emerging global health concern. Although new guidelines are developed for facilitating clinical management, the reasons for the prevalence of hypertension in children remain unknown. Genetics and environmental factors do not fully account for the growing incidence of pediatric hypertension. Because stable bacterial flora in early life are linked with health outcomes later in life, we hypothesized that reshaping of gut microbiota in early life affects blood pressure (BP) of pediatric subjects. Methods and Results: To test this hypothesis, we administered amoxicillin, the most commonly prescribed pediatric antibiotic, to alter gut microbiota of young, genetically hypertensive rats (study 1) and dams during gestation and lactation (study 2) and recorded their BP. Reshaping of microbiota with reductions in Firmicutes/Bacteriodetes ratio were observed. Amoxicillin treated rats had lower BP compared with untreated rats. In young rats treated with amoxicillin, the lowering effect on BP persisted even after antibiotics were discontinued. Similarly, offspring from dams treated with amoxicillin showed lower systolic BP compared with control rats. Remarkably, in all cases, a decrease in BP was associated with lowering of Veillonellaceae, which are succinate‐producing bacteria. Elevated plasma succinate is reported in hypertension. Accordingly, serum succinate was measured and found lower in animals treated with amoxicillin. Conclusions: Our results demonstrate a direct correlation between succinate‐producing gut microbiota and early development of hypertension and indicate that reshaping gut microbiota, especially by depleting succinate‐producing microbiota early in life, may have long‐term benefits for hypertension‐prone individuals.Hide Abstract
Photosynthetic co-production of succinate and ethylene in a fast-growing cyanobacterium, Synechococcus elongatus PCC 11801.
Sengupta, A., Pritam, P., Jaiswal, D., Bandyopadhyay, A., Pakrasi, H. B. & Wangikar, P. P. (2020). Metabolites, 10(6), 250.
Cyanobacteria are emerging as hosts for photoautotrophic production of chemicals. Recent studies have attempted to stretch the limits of photosynthetic production, typically focusing on one product at a time, possibly to minimise the additional burden of product separation. Here, we explore the simultaneous production of two products that can be easily separated: ethylene, a gaseous product, and succinate, an organic acid that accumulates in the culture medium. This was achieved by expressing a single copy of the ethylene forming enzyme (efe) under the control of PcpcB, the inducer-free super-strong promoter of phycocyanin β subunit. We chose the recently reported, fast-growing and robust cyanobacterium, Synechococcus elongatus PCC 11801, as the host strain. A stable recombinant strain was constructed using CRISPR-Cpf1 in a first report of markerless genome editing of this cyanobacterium. Under photoautotrophic conditions, the recombinant strain shows specific productivities of 338.26 and 1044.18 μmole/g dry cell weight/h for ethylene and succinate, respectively. These results compare favourably with the reported productivities for individual products in cyanobacteria that are highly engineered. Metabolome profiling and 13C labelling studies indicate carbon flux redistribution and suggest avenues for further improvement. Our results show that S. elongatus PCC 11801 is a promising candidate for metabolic engineering.Hide Abstract
Statistical Modelization of the Descriptor “Minerality” Based on the Sensory Properties and Chemical Composition of Wine.
Zaldívar Santamaría, E., Molina Dagá, D. & Palacios García, A. T. (2019). Beverages, 5(4), 66.
When speaking of “minerality” in wines, it is common to find descriptive terms in the vocabulary of wine tasters such as flint, match smoke, kerosene, rubber eraser, slate, granite, limestone, earthy, tar, charcoal, graphite, rock dust, wet stones, salty, metallic, steel, ferrous, etc. These are just a few of the descriptors that are commonly found in the tasting notes of wines that show this sensory profile. However, not all wines show this mineral trace at the aromatic and gustatory level. This study has used the statistical tool partial least squares regression (PLS) to mathematically model the attribute of “minerality” of wine, thereby obtaining formulas where the chemical composition and sensory attributes act jointly as the predictor variables, both for white wines and red wines, so as to help understand the term and to devise a winemaking approach able to endow wines with this attribute if desired.Hide Abstract
Metschnikowia pulcherrima selected strain for ethanol reduction in wine: Influence of cell immobilization and aeration condition.
Canonico, L., Comitini, F. & Ciani, M. (2019). Foods, 8(9), 378.
One of the most important problems in the winemaking field is the increase of ethanol content in wine. Wines with high ethanol level negatively affect wine flavor and human health. In this study, we evaluated the use of a selected strain of Metschnikowia pulcherrima in immobilized form and under different aeration conditions, to reduce the ethanol content evaluating the volatile profile of the resulting wines. In a preliminary screening the best conditions regarding free/immobilized cells, static/aerated fermentation and inoculation level were identified. Bench-Top fermentation trials with different aeration conditions showed that the use of M. pulcherrima selected strain with aeration flow of 20 mL/L/min during the first 72 h of fermentation, led an ethanol reduction of 1.38% (v/v) in comparison with Saccharomyces cerevisiae control strain. The analytical profile of the resulting wines did not show any negative feature. Indeed, the concentration of ethyl acetate, that above its sensory threshold impacts negatively the wine sensory profile, was found at an acceptable level. On the other hand, an increase in the concentration of significant fruity and flower compounds was found.Hide Abstract
Production of 5-aminolevulinic Acid by Recombinant Streptomyces coelicolor Expressing hemA from Rhodobacter sphaeroides.
Tran, N. T., Pham, D. N. & Kim, C. J. (2019). Biotechnology and Bioprocess Engineering, 24(3), 488-499.
Over the past two decades, intensive efforts have been made to construct recombinant Escherichia coli or Corynebacterium glutamicum by engineering C4 or C5 pathways to improve microbial production of 5-aminolevulinic acid (ALA), which has medical application for photodynamic cancer therapy and tumor diagnosis. In this study, we explored the feasibility of enhanced production of ALA by expressing C4 pathway enzyme, ALA synthase, in Streptomyces coelicolor, and medium optimization. The hemA from Rhodobacter sphaeroides was successfully integrated into the chromosome of Streptomyces coelicolor by conjugal transformation, and recombinant Streptomyces cells expressed well the foreign hemA. Glucose promoted ALA synthesis, and yeast extract showed a strong positive effect on ALA production. Optimization of casamino acid, peptone, malt extract, glycine, and succinic acid increased the product titer. In flask cultures, cell growth and ALA production of recombinant Streptomyces were 2.3 and 3.0-fold higher, respectively, in optimal medium than those of control. The maximum ALA, 137 mg/L, was obtained at 28 h in bioreactor culture, in which 3.1-fold higher cell mass and 2.9-fold greater volumetric productivity were achieved, compared to those in flask cultures.Hide Abstract
Cereal fructan extracts alter intestinal fermentation to reduce adiposity and increase mineral retention compared to oligofructose.
Belobrajdic, D. P., Jenkins, C. L., Christophersen, C. T. & Bird, A. R. (2019). European Journal of Nutrition, 58(7), 2811-2821.
Purpose: Intestinal fermentation of inulin-type fructans, including oligofructose, can modulate adiposity, improve energy regulation, and increase mineral absorption. We aimed to determine whether cereal fructans had greater effects on reducing adiposity and improving mineral absorption compared with oligofructose. Methods: Thirty-two male Sprague–Dawley rats were randomly assigned to one of four dietary treatments that contained 0% fructan (control), or 5% fructan provided by oligofructose (OF), a barley grain fraction (BGF), or a wheat stem fraction (WSF). After 1 week on the diets, mineral absorption and retention was assessed. At 4 weeks, blood samples were collected for gut hormone analysis, adipose depots were removed and weighed, and caecal digesta was analyzed for pH and short-chain fatty acids (SCFA). Results: The BGF and WSF, but not OF, had lower total visceral fat weights than the Control (p < 0.05). The fructan diets all lowered caecal pH and raised caecal digesta weight and total SCFA content, in comparison to the Control. Caecal propionate levels for OF were similar to the Control and higher for WSF (p < 0.05). Plasma peptide YY and glucagon-like peptide-1 levels were elevated for all fructan groups when compared to Control (p < 0.001) and gastric inhibitory peptide was lower for the WSF compared to the other groups (p < 0.05). The fructan diets improved calcium and magnesium retention, which was highest for WSF (p < 0.05). BGF and WSF in comparison to OF showed differential effects on fermentation, gut hormone levels, and adiposity. Conclusions: Cereal fructan sources have favorable metabolic effects that suggest greater improvements in energy regulation and mineral status to those reported for oligofructose.Hide Abstract
van Diepen, J. A., Robben, J. H., Hooiveld, G. J., Carmone, C., Alsady, M., Boutens, L., Bekkenkamp-Grovenstein, M. B., Hijmans, A., Engelke, U. F. H.,Wevers, R. A., Netea, M. G., Tack, C. J., Stienstra, R. & Deen, P. M. T. (2017). Diabetologia, 1-10.
Aims/hypothesis: Obesity induces macrophages to drive inflammation in adipose tissue, a crucial step towards the development of type 2 diabetes. The tricarboxylic acid (TCA) cycle intermediate succinate is released from cells under metabolic stress and has recently emerged as a metabolic signal induced by proinflammatory stimuli. We therefore investigated whether succinate receptor 1 (SUCNR1) could play a role in the development of adipose tissue inflammation and type 2 diabetes. Methods: Succinate levels were determined in human plasma samples from individuals with type 2 diabetes and non-diabetic participants. Succinate release from adipose tissue explants was studied. Sucnr1-/- and wild-type (WT) littermate mice were fed a high-fat diet (HFD) or low-fat diet (LFD) for 16 weeks. Serum metabolic variables, adipose tissue inflammation, macrophage migration and glucose tolerance were determined. Results: We show that hypoxia and hyperglycaemia independently drive the release of succinate from mouse adipose tissue (17-fold and up to 18-fold, respectively) and that plasma levels of succinate were higher in participants with type 2 diabetes compared with non-diabetic individuals (+53%; p < 0.01). Sucnr1-/- mice had significantly reduced numbers of macrophages (0.56 ± 0.07 vs 0.92 ± 0.15 F4/80 cells/adipocytes, p < 0.05) and crown-like structures (0.06 ± 0.02 vs 0.14 ± 0.02, CLS/adipocytes p < 0.01) in adipose tissue and significantly improved glucose tolerance (p < 0.001) compared with WT mice fed an HFD, despite similarly increased body weights. Consistently, macrophages from Sucnr1-/- mice showed reduced chemotaxis towards medium collected from apoptotic and hypoxic adipocytes (−59%; p < 0.05). Conclusions/interpretation: Our results reveal that activation of SUCNR1 in macrophages is important for both infiltration and inflammation of adipose tissue in obesity, and suggest that SUCNR1 is a promising therapeutic target in obesity-induced type 2 diabetes.Hide Abstract
Zander, D., Samaga, D., Straube, R. & Bettenbrock, K. (2017). Biophysical Journal, 112(9), 1984-1996.
The Escherichia coli lac operon is regulated by a positive feedback loop whose potential to generate an all-or-none response in single cells has been a paradigm for bistable gene expression. However, so far bistable lac induction has only been observed using gratuitous inducers, raising the question about the biological relevance of bistable lac induction in the natural setting with lactose as the inducer. In fact, the existing experimental evidence points to a graded rather than an all-or-none response in the natural lactose uptake system. In contrast, predictions based on computational models of the lactose uptake pathway remain controversial. Although some argue in favor of bistability, others argue against it. Here, we reinvestigate lac operon expression in single cells using a combined experimental/modeling approach. To this end, we parameterize a well-supported mathematical model using transient measurements of LacZ activity upon induction with different amounts of lactose. The resulting model predicts a monostable induction curve for the wild-type system, but indicates that overexpression of the LacI repressor would drive the system into the bistable regime. Both predictions were confirmed experimentally supporting the view that the wild-type lac induction circuit generates a graded response rather than bistability. More interestingly, we find that the lac induction curve exhibits a pronounced maximum at intermediate lactose concentrations. Supported by our data, a model-based analysis suggests that the nonmonotonic response results from saturation of the LacI repressor at low inducer concentrations and dilution of Lac enzymes due to an increased growth rate beyond the saturation point. We speculate that the observed maximum in the lac expression level helps to save cellular resources by limiting Lac enzyme expression at high inducer concentrations.Hide Abstract
Boonsaen, P., Kinjo, M., Sawanon, S., Suzuki, Y., Koike, S. & Kobayashi, Y. (2017). Animal Science Journal, In Press.
The fibrolytic rumen bacterium Ruminococcus flavefaciens OS14 was isolated from swamp buffalo and its phylogenetic, ecological and digestive properties were partially characterized. Isolates from rumen contents of four swamp buffalo were screened for fibrolytic bacteria; one of the 40 isolates showed a distinctive feature of solubilizing cellulose powder in liquid culture and was identified as R. flavefaciens based on its 16S ribosomal DNA sequence. This isolate, OS14, was employed for detection and digestion studies, for which a quantitative PCR assay was developed and defined cultures were tested with representative forages in Thailand. OS14 was phylogenetically distant from other isolated and uncultured R. flavefaciens and showed limited distribution among Thai ruminants but was absent in Japanese cattle. OS14 digested rice straw and other tropical forage to a greater extent than the type strain C94 of R. flavefaciens. OS14 produced more lactate than C94, and digested para grass to produce propionate more extensively in co-culture with lactate-utilizing Selenomonas ruminantium S137 than a co-culture of C94 with S137. These results indicate that phylogenetically distinct OS14 could digest Thai local forage more efficiently than the type strain, possibly forming a symbiotic cross-feeding relationship with lactate-utilizing bacteria. This strain might be useful for future animal and other industrial applications.Hide Abstract
Chidi, B. S., Rossouw, D. & Bauer, F. F. (2016). Current genetics, 62(1), 149-164.
Saccharomyces cerevisiae strains used for winemaking show a wide range of fermentation phenotypes, and the genetic background of individual strains contributes significantly to the organoleptic properties of wine. This strain-dependent impact extends to the organic acid composition of the wine, an important quality parameter. However, little is known about the genes which may impact on organic acids during grape must fermentation. To generate novel insights into the genetic regulation of this metabolic network, a subset of genes was identified based on a comparative analysis of the transcriptomes and organic acid profiles of different yeast strains showing different production levels of organic acids. These genes showed significant inter-strain differences in their transcription levels at one or more stages of fermentation and were also considered likely to influence organic acid metabolism based on existing functional annotations. Genes selected in this manner were ADH3, AAD6, SER33, ICL1, GLY1, SFC1, SER1, KGD1, AGX1, OSM1 and GPD2. Yeast strains carrying deletions for these genes were used to conduct fermentations and determine organic acid levels at various stages of alcoholic fermentation in synthetic grape must. The impact of these deletions on organic acid profiles was quantified, leading to novel insights and hypothesis generation regarding the role/s of these genes in wine yeast acid metabolism under fermentative conditions. Overall, the data contribute to our understanding of the roles of selected genes in yeast metabolism in general and of organic acid metabolism in particular.Hide Abstract
Nikel, P. I., Chavarría, M., Fuhrer, T., Sauer, U. & de Lorenzo, V. (2015). Journal of Biological Chemistry, 290(43), 25920-25932.
The soil bacterium Pseudomonas putida KT2440 lacks a functional Embden-Meyerhof-Parnas (EMP) pathway, and glycolysis is known to proceed almost exclusively through the Entner-Doudoroff (ED) route. To investigate the raison d'être of this metabolic arrangement, the distribution of periplasmic and cytoplasmic carbon fluxes was studied in glucose cultures of this bacterium by using 13C-labeled substrates, combined with quantitative physiology experiments, metabolite quantification, and in vitro enzymatic assays under both saturating and non-saturating, quasi in vivo conditions. Metabolic flux analysis demonstrated that 90% of the consumed sugar was converted into gluconate, entering central carbon metabolism as 6-phosphogluconate and further channeled into the ED pathway. Remarkably, about 10% of the triose phosphates were found to be recycled back to form hexose phosphates. This set of reactions merges activities belonging to the ED, the EMP (operating in a gluconeogenic fashion), and the pentose phosphate pathways to form an unforeseen metabolic architecture (EDEMP cycle). Determination of the NADPH balance revealed that the default metabolic state of P. putida KT2440 is characterized by a slight catabolic overproduction of reducing power. Cells growing on glucose thus run a biochemical cycle that favors NADPH formation. Because NADPH is required not only for anabolic functions but also for counteracting different types of environmental stress, such a cyclic operation may contribute to the physiological heftiness of this bacterium in its natural habitats.Hide Abstract