Pathways Of Glucose Catabolism Research Articles

Adaptation of Glucose Metabolism to Limb Autotomy and Regeneration in the Chinese Mitten Crab.

Limb autotomy and regeneration represent distinctive responses of crustaceans to environmental stress. Glucose metabolism plays a pivotal role in energy generation for tissue development and regeneration across various species. However, the relationship between glucose metabolism and tissue regeneration in crustaceans remains elusive. Therefore, this study is aimed at analyzing the alterations of glucose metabolic profile during limb autotomy and regeneration in Eriocheir sinensis, while also evaluating the effects of carbohydrate supplementation on limb regeneration. The results demonstrated that limb autotomy triggered a metabolic profile adaption at the early stage of regeneration. Hemolymph glucose levels were elevated, and multiple glucose catabolic pathways were enhanced in the hepatopancreas. Additionally, glucose and ATP levels in the regenerative limb were upregulated, along with increased expression of glucose transporters. Furthermore, the gene expression and activity of enzymes involved in gluconeogenesis were repressed in the hepatopancreas. These findings indicate that limb regeneration triggers metabolic profile adaptations to meet the elevated energy requirements. Moreover, the study observed that supplementation with corn starch enhanced limb regeneration capacity by promoting wound healing and blastema growth. Interestingly, dietary carbohydrate addition influenced limb regeneration by stimulating gluconeogenesis rather than glycolysis in the regenerative limb. Thus, these results underscore the adaptation of glucose metabolism during limb autotomy and regeneration, highlighting its essential role in the limb regeneration process of E. sinensis.

Phosphofructokinase family genes in grass carp: Molecular identification and tissue-specific expression in response to glucose, insulin and glucagon.

It is widely acknowledged that glucose serves as the primary energy source for organisms. However, fish exhibit persistent postprandial hyperglycemia and are thought to have low glucose tolerance. Glycolysis serves as the ubiquitous pathway for glucose catabolism, with phosphofructokinase (PFK) acting as a crucial rate-limiting enzyme in this process and playing an indispensable role. PFK is classified into three isoforms based on their major expression sites, i.e., PFKM (skeletal muscle type), PFKL (liver type) and PFKP (platelet type). In this study, grass carp (Ctenopharyngodon idella) was used as animal model and the open reading frame (ORF) sequences of six PFK genetic isoforms of grass carp were cloned. Real-time PCR was used to detect its tissue distribution, and expression changes in oral glucose tolerance test (OGTT), insulin and glucagon injection experiments. The results showed that the ORF of pfkla, pfklb, pfkma, pfkmb, pfkpa and pfkpb genes was 2343, 2340, 2355, 2331, 2364 and 2349bp in length, respectively. The results of tissue distribution showed that pfkla and pfklb, homologous to mammalian pfkl, exhibited low expression levels in the liver of grass carp, but were expressed at the highest level in the brain. Muscle-type pfkma and pfkmb mRNA were found to be highly expressed in both red and white muscle, with pfkmb also exhibiting high expression levels in the heart, while platelet type pfkpa and pfkpb showed high mRNA abundances in the brain and heart. Oral glucose administration stimulated pfkma and pfkmb mRNA expression in the red muscle, and up-regulated pfklb mRNA levels in the liver at 3h post treatment, but it suppressed liver-type and platelet-type PFK genes expression in the brain. The expression of pfkmb in white muscle and pfkmb and pfkpb in heart were promoted by insulin, whereas the expression of pfkla and pfkpb in the brain, pfkma and pfkmb in the red muscle, pfkma in the white muscle, and pfklb in the liver was suppressed by insulin. As for glucagon, it inhibited pfkma and pfkmb mRNA expression in the red muscle, as well as pfklb in the liver, but it up-regulated PFK genes expression in most tissues detected, such as brain (pfklb, pfkpa and pfkpb), white muscle (pfkma and pfkmb), liver (pfkla) and heart (pfkmb and pfkpb). Our results suggest that PFK family genes have different or even opposite expression patterns in response to glucose, insulin and glucagon stimulation in various tissues of grass carp, which may contribute to glucose intolerance in fish.

Cell-Type Specific Requirement of Glucose Catabolism in Erythropoiesis and Thymopoiesis

Glucose catabolism through glycolysis is central to cellular life. In glycolysis, pyruvate is converted to lactate by lactate dehydrogenase (LDH) or oxidized into the tricarboxylic acid (TCA) cycle via acetyl-CoA by pyruvate dehydrogenase (PDH). However, the two enzymes LDH and PDH required for completing glucose catabolism have never been ablated simultaneously in any tissue in vivo to test if glycolysis is required for cell survival and function. Ldha and Ldhb, the genes coding for LDH have not been ablated simultaneously in in the erythroid lineage to test if LDH plays a significant role in erythropoiesis. It is also unknown if erythoid progenitor cells, which unlike mature erythrocytes contain mitochondria, rely on LDH or are able to oxidize glucose via PDH to support erythroid development. To address these questions, we have generated conditional genetic knockouts (KO) of Ldha, Ldhb and PDH ( Pdha1) in the hematopoietic system to study the requirement of glucose catabolism in erythropoiesis. We observed that Ldha Δ/Δ and Ldha Δ/Δ;Ldhb Δ/Δ but not Ldhb Δ / Δmice had anemia, consistent with an essential role for LDHA in erythrocytes or erythropoiesis. Anemia was more severe in Ldha Δ/Δ;Pdha1 Δ mice as compared to Ldha Δ/Δ mice suggesting LDH and PDH are required in concert to maintain erythroid development in vivo. Ldha Δ/Δ mice accumulated CD71 +Ter119 + erythroid progenitors but Ldha Δ/Δ;Pdha1 Δ knockout mice had a significant decrease in this population. Moreover, there was a more pronounced expansion of upstream CD71 -Ter119 int and CD71 +Ter119 int cells in Ldha Δ/Δ;Pdha1 Δmice. This suggest that the accumulation of CD71 +Ter119 + cells in Ldha Δ/Δ mice is dependent on PDH and that the presence of either LDHA or PDH is required for the progression from CD71 +Ter119 int to CD71 +Ter119 + erythroid progenitors. The bone marrow of Ldha Δ/Δ;Pdha1 Δ showed an accumulation of pre-CFU-E and a depletion of CFU-E cells as compared to single Ldha Δ/Δ mice. Therefore, the presence of either LDHA or PDH is required to transit from pre-CFU-E to CFU-E stage during erythroid differentiation. Our previous results show that PDH is required for the double positive (DP) stage of T cell development. Analysis of thymus of Ldha Δ/Δ and Ldha Δ/Δ;Ldhb Δ/Δ mice did not show any changes in thymocytes. However, Ldha Δ/Δ;Pdha1 Δmice showed a significant decrease at the double negative (DN1) stage which persisted through all T cell development stages. Given that, PDH is required at the double positive (DP) stage and LDH deficiency alone does not affect T cell development, this suggest that LDH and PDH act redundantly at different stages to support T cell development. Altogether, these results suggest cell-type specific usage of glucose catabolic pathways in different differentiation stages. Our results also suggest that progenitor cells can switch between LDH and PDH for glucose catabolism while mature immune cells rely on either LDH or PDH for survival. To investigate this, we will use metabolomics and isotope tracing methods to analyze the route of glucose catabolism during erythroid and T cell development.

Flux regulation through glycolysis and respiration is balanced by inositol pyrophosphates in yeast

Although many prokaryotes have glycolysis alternatives, it's considered as the only energy-generating glucose catabolic pathway in eukaryotes. Here, we managed to create a hybrid-glycolysis yeast. Subsequently, we identified an inositol pyrophosphatase encoded by OCA5 that could regulate glycolysis and respiration by adjusting 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP7) levels. 5-InsP7 levels could regulate the expression of genes involved in glycolysis and respiration, representing a global mechanism that could sense ATP levels and regulate central carbon metabolism. The hybrid-glycolysis yeast did not produce ethanol during growth under excess glucose and could produce 2.68 g/L free fatty acids, which is the highest reported production in shake flask of Saccharomyces cerevisiae. This study demonstrated the significance of hybrid-glycolysis yeast and determined Oca5 as an inositol pyrophosphatase controlling the balance between glycolysis and respiration, which may shed light on the role of inositol pyrophosphates in regulating eukaryotic metabolism.

Direct conversion of carbon dioxide to glucose using metabolically engineered Cupriavidus necator

Artificial synthesis of glucose, the monomer of starch, from renewable resources and CO2 is a promising method for addressing food crisis and alleviating climate change. Here, the construction of a microbial biocatalyst for glucose production from renewable resources and CO2 was reported. Initially, blocking the glucose catabolic pathway via deletion of glk gene generated a glucose-producing strain of Cupriavidus necator with titers of 24.7, 47.5 and 180.1 mg/L from fructose, glycerol and CO2, respectively. Subsequently, the Entner-Doudoroff pathway and polyhydroxybutyrate biosynthesis pathway were disrupted to further increase glucose accumulation. The maximum glucose titer and yield on biomass from CO2 reached 253.3 mg/L and 91.6 mg/L/OD600, respectively. Finally, the phosphatases that mediate the dephosphorylation of phosphorylated glucose were identified. Overexpression of HAD1 and cbbY2 could enhance glucose titer by 5.5-fold when fructose was used as sole carbon source. This study demonstrates a feasible route for microbial-based synthesis of glucose from CO2.

Comparative transcriptomic and lipidomic analysis of oleic environment adaptation in Saccharomyces cerevisiae: insight into metabolic reprogramming and lipid membrane expansion

With staggering progress on genetic manipulation strategies, Saccharomyces cerevisiae is becoming an ideal cell factory for the de novo biosynthesis of lipid compounds. However, due to their hydrophobicity, lipids tend to be accumulated within intracellular spaces and cause a high burden on cell activity and induce product inhibition effect, which ultimately restricted the lipids biomanufacturing for industrial application. Herein, an oleic acid stress (OAS) model was applied for the long-time domestication of BY4741 cells, and a subclone of A-22 was obtained through a series of acclimation (0.1% glucose and 0.2% oleic acid), showing increased accumulation of both biomass and intracellular lipid droplets compared to WT. Comparative transcriptome analysis indicated that compared to fatty acid metabolism, most transcripts enriched in the pathways of glucose catabolism (glycolysis and citrate cycle) and lipid synthesis (phospholipid and sterol) were down-regulated under OAS. While interestingly, most the above transcripts tended to be ‘restored’ in adapted strain A-22. In addition, for physical adaptation, significant increase of phosphatidylcholines was identified by lipidomic analysis, which probably caused the subsequent subcellular expansion of peroxisomes and lipid droplets as observed in the adapted strain, since phosphatidylcholines are the major constituent of their membranes. The present study systematically investigated both the phenotype change and molecular mechanism on adaptation of S. cerevisiae towards oily environment. Detailed information on functional transcripts may provide novel rational modification targets to reinforce the hydrophobic lipids biosynthesis within S. cerevisiae engineered cell factory.

Synergetic Fermentation of Glucose and Glycerol for High-Yield N-Acetylglucosamine Production in Escherichia coli.

N-acetylglucosamine (GlcNAc) is an amino sugar that has been widely used in the nutraceutical and pharmaceutical industries. Recently, microbial production of GlcNAc has been developed. One major challenge for efficient biosynthesis of GlcNAc is to achieve appropriate carbon flux distribution between growth and production. Here, a synergistic substrate co-utilization strategy was used to address this challenge. Specifically, glycerol was utilized to support cell growth and generate glutamine and acetyl-CoA, which are amino and acetyl donors, respectively, for GlcNAc biosynthesis, while glucose was retained for GlcNAc production. Thanks to deletion of the 6-phosphofructokinase (PfkA and PfkB) and glucose-6-phosphate dehydrogenase (ZWF) genes, the main glucose catabolism pathways of Escherichia coli were blocked. The resultant mutant showed a severe defect in glucose consumption. Then, the GlcNAc production module containing glucosamine-6-phosphate synthase (GlmS*), glucosamine-6-phosphate N-acetyltransferase (GNA1*) and GlcNAc-6-phosphate phosphatase (YqaB) expression cassettes was introduced into the mutant, to drive the carbon flux from glucose to GlcNAc. Furthermore, co-utilization of glucose and glycerol was achieved by overexpression of glycerol kinase (GlpK) gene. Using the optimized fermentation medium, the final strain produced GlcNAc with a high stoichiometric yield of 0.64 mol/mol glucose. This study offers a promising strategy to address the challenge of distributing carbon flux in GlcNAc production.

Stable Isotope-Resolved Metabolomics Reveals the Abnormal Brain Glucose Catabolism in Depression Based on Chronic Unpredictable Mild Stress Rats.

The severe harm of depression to human life has attracted great attention to neurologists, but its pathogenesis is extremely complicated and has not yet been fully elaborated. Here, we provided a new strategy for revealing the specific pathways of abnormal brain glucose catabolism in depression, based on the supply of energy substrates and the evaluation of the mitochondrial structure and function. By using stable isotope-resolved metabolomics, we discovered that the tricarboxylic acid cycle (TCA cycle) is blocked and gluconeogenesis is abnormally activated in chronic unpredictable mild stress (CUMS) rats. In addition, our results showed an interesting phenomenon that the brain attempted to activate all possible metabolic enzymes in energy-producing pathways, but CUMS rats still exhibited a low TCA cycle activity due to impaired mitochondria. Depression caused the mitochondrial structure and function to be impaired and then led to abnormal brain glucose catabolism. The combination of the stable isotope-resolved metabolomics and mitochondrial structure and function analysis can accurately clarify the mechanism of depression. The mitochondrial pyruvate carrier and acetyl-CoA may be the key targets for depression treatment. The strategy provides a unique insight for exploring the mechanism of depression, the discovery of new targets, and the development of ideal novel antidepressants. Data are available via ProteomeXchange with identifier PXD025548.

Role of cAMP in Double Switch of Glucagon Secretion.

Glucose metabolism plays a crucial role in modulating glucagon secretion in pancreatic alpha cells. However, the downstream effects of glucose metabolism and the activated signaling pathways influencing glucagon granule exocytosis are still obscure. We developed a computational alpha cell model, implementing metabolic pathways of glucose and free fatty acids (FFA) catabolism and an intrinsically activated cAMP signaling pathway. According to the model predictions, increased catabolic activity is able to suppress the cAMP signaling pathway, reducing exocytosis in a Ca2+-dependent and Ca2+ independent manner. The effect is synergistic to the pathway involving ATP-dependent closure of KATP channels and consequent reduction of Ca2+. We analyze the contribution of each pathway to glucagon secretion and show that both play decisive roles, providing a kind of “secure double switch”. The cAMP-driven signaling switch plays a dominant role, while the ATP-driven metabolic switch is less favored. The ratio is approximately 60:40, according to the most recent experimental evidence.

BCKDK regulates the TCA cycle through PDC in the absence of PDK family during embryonic development.

Pyruvate dehydrogenase kinases (PDK1-4) inhibit the TCA cycle by phosphorylating pyruvate dehydrogenase complex (PDC). Here, we show that PDK family is dispensable for murine embryonic development and that BCKDK serves as a compensatory mechanism by inactivating PDC. First, we knocked out all four Pdk genes one by one. Surprisingly, Pdk total KO embryos developed and were born in expected ratios but died by postnatal day 4 because of hypoglycemia or ketoacidosis. Moreover, PDC was phosphorylated in these embryos, suggesting that another kinase compensates for PDK family. Bioinformatic analysis implicated branched-chain ketoacid dehydrogenase kinase (Bckdk), a key regulator of branched-chain amino acids (BCAAs) catabolism. Indeed, knockout of Bckdk and Pdk family led to the loss of PDC phosphorylation, an increase in PDC activity and pyruvate entry into the TCA cycle, and embryonic lethality. These findings reveal a regulatory crosstalk hardwiring BCAA and glucose catabolic pathways, which feed the TCA cycle.

Genetic Perturbation of Pyruvate Dehydrogenase Kinase 1 Modulates Growth, Angiogenesis and Metabolic Pathways in Ovarian Cancer Xenografts.

Pyruvate dehydrogenase kinase 1 (PDK1) blockade triggers are well characterized in vitro metabolic alterations in cancer cells, including reduced glycolysis and increased glucose oxidation. Here, by gene expression profiling and digital pathology-mediated quantification of in situ markers in tumors, we investigated effects of PDK1 silencing on growth, angiogenesis and metabolic features of tumor xenografts formed by highly glycolytic OC316 and OVCAR3 ovarian cancer cells. Notably, at variance with the moderate antiproliferative effects observed in vitro, we found a dramatic negative impact of PDK1 silencing on tumor growth. These findings were associated with reduced angiogenesis and increased necrosis in the OC316 and OVCAR3 tumor models, respectively. Analysis of viable tumor areas uncovered increased proliferation as well as increased apoptosis in PDK1-silenced OVCAR3 tumors. Moreover, RNA profiling disclosed increased glucose catabolic pathways—comprising both oxidative phosphorylation and glycolysis—in PDK1-silenced OVCAR3 tumors, in line with the high mitotic activity detected in the viable rim of these tumors. Altogether, our findings add new evidence in support of a link between tumor metabolism and angiogenesis and remark on the importance of investigating net effects of modulations of metabolic pathways in the context of the tumor microenvironment.

Core Fermentation (CoFe) granules focus coordinated glycolytic mRNA localization and translation to fuel glucose fermentation

SummaryGlycolysis is a fundamental metabolic pathway for glucose catabolism across biology, and glycolytic enzymes are among the most abundant proteins in cells. Their expression at such levels provides a particular challenge. Here we demonstrate that the glycolytic mRNAs are localized to granules in yeast and human cells. Detailed live cell and smFISH studies in yeast show that the mRNAs are actively translated in granules, and this translation appears critical for the localization. Furthermore, this arrangement is likely to facilitate the higher level organization and control of the glycolytic pathway. Indeed, the degree of fermentation required by cells is intrinsically connected to the extent of mRNA localization to granules. On this basis, we term these granules, core fermentation (CoFe) granules; they appear to represent translation factories, allowing high-level coordinated enzyme synthesis for a critical metabolic pathway.

Metabolic flux ratio analysis by parallel 13C labeling of isoprenoid biosynthesis in Rhodobacter sphaeroides

Metabolic engineering for increased isoprenoid production often benefits from the simultaneous expression of the two naturally available isoprenoid metabolic routes, namely the 2-methyl-D-erythritol 4-phosphate (MEP) pathway and the mevalonate (MVA) pathway. Quantification of the contribution of these pathways to the overall isoprenoid production can help to obtain a better understanding of the metabolism within a microbial cell factory. Such type of investigation can benefit from 13C metabolic flux ratio studies. Here, we designed a method based on parallel labeling experiments (PLEs), using [1-13C]- and [4-13C]glucose as tracers to quantify the metabolic flux ratios in the glycolytic and isoprenoid pathways. By just analyzing a reporter isoprenoid molecule and employing only four equations, we could describe the metabolism involved from substrate catabolism to product formation. These equations infer 13C atom incorporation into the universal isoprenoid building blocks, isopentenyl-pyrophosphate (IPP) and dimethylallyl-pyrophosphate (DMAPP). Therefore, this renders the method applicable to the study of any of isoprenoid of interest. As proof of principle, we applied it to study amorpha-4,11-diene biosynthesis in the bacterium Rhodobacter sphaeroides. We confirmed that in this species the Entner-Doudoroff pathway is the major pathway for glucose catabolism, while the Embden-Meyerhof-Parnas pathway contributes to a lesser extent. Additionally, we demonstrated that co-expression of the MEP and MVA pathways caused a mutual enhancement of their metabolic flux capacity. Surprisingly, we also observed that the isoprenoid flux ratio remains constant under exponential growth conditions, independently from the expression level of the MVA pathway. Apart from proposing and applying a tool for studying isoprenoid biosynthesis within a microbial cell factory, our work reveals important insights from the co-expression of MEP and MVA pathways, including the existence of a yet unclear interaction between them.

Bacterial Acid Resistance Toward Organic Weak Acid Revealed by RNA-Seq Transcriptomic Analysis in Acetobacter pasteurianus.

Under extreme acidic environments, bacteria exploit several acid resistance (AR) mechanisms for enhancing their survival, which is concerned with several aspects, such as issues in human health and fermentation for acidic products. Currently, knowledge of bacterial AR mainly comes from the strong acid (such as hydrochloric acid) stresses, whereas AR mechanisms against organic weak acids (such as acetic acid), which are indeed encountered by bacteria, are less understood. Acetic acid bacteria (AAB), with the ability to produce acetic acid up to 20 g/100 mL, possess outstanding acetic acid tolerance, which is conferred by their unique AR mechanisms, including pyrroloquinoline quinine-dependent alcohol dehydrogenase, acetic acid assimilation and molecular chaperons. The distinguished AR of AAB toward acetic acid may provide a paradigm for research in bacterial AR against weak organic acids. In order to understand AAB’s AR mechanism more holistically, omics approaches have been employed in the corresponding field. However, the currently reported transcriptomic study was processed under a low-acidity (1 g/100 mL) environment, which could not reflect the general conditions that AAB are usually faced with. This study performed RNA-Seq transcriptomic analysis investigating AR mechanisms in Acetobacter pasteurianus CGMCC 1.41, a widely used vinegar-brewing AAB strain, at different stages of fermentation, namely, under different acetic acid concentrations (from 0.6 to 6.03 g/100 mL). The results demonstrated the even and clustered genomic distribution of up- and down-regulated genes, respectively. Difference in AR between AAB and other microorganisms was supported by the down-regulation of urea degradation and trehalose synthesis-related genes in response to acetic acid. Detailed analysis reflected the role of ethanol respiration as the main energy source and the limited effect of acetic acid assimilation on AR during fermentation as well as the competition between ethanol respiratory chain and NADH, succinate dehydrogenase-based common respiratory chain. Molecular chaperons contribute to AR, too, but their regulatory mechanisms require further investigation. Moreover, pathways of glucose catabolism and fatty acid biosynthesis are also related to AR. Finally, 2-methylcitrate cycle was proposed as an AR mechanism in AAB for the first time. This study provides new insight into AR mechanisms of AAB, and it also indicates the existence of numerous undiscovered AR mechanisms.

Study of characteristics on metabolism of Penicillium chrysogenum F1 during bioleaching of heavy metals from contaminated soil.

Penicillium chrysogenum F1 is very efficient in bioleaching heavy metals from the soil and is used for that purpose. We found that F1 can extract 19.8 mg Cd, Cu, Pb, and Zn from 2.5 g soil; the total heavy metals' bioleaching ratio was 60.4%. In this study, the bioleaching mechanism was investigated by means of metabonomics; different metabolite ions were screened (relative standard deviation >30%) and analyzed using clustering, univariate and multivariate analysis. Statistical analyses via Volcano Plot, principal component analysis, and partial least square discriminant analysis models revealed a difference between Ctrl 7 (the controls cultured and sampled on day 7) and Ctrl 15 (the controls cultured and sampled on day 15). Samp 15 (the samples cultured with heavy-metal-contaminated soil) was significantly different from Ctrl 7 and Ctrl 15. Analysis of the different ions demonstrated that the glucose catabolism pathways of glycolysis and the tricarboxylic acid (TCA) cycle were enhanced, and glucose anabolism through the pentose phosphate pathway was inhibited during bioleaching. At the same time, the metabolism of glutathione was also downregulated. Therefore, the catabolism of glucose was unaffected by the addition of heavy-metal-contaminated soil, and increasing glucose is beneficial to catabolism. The extraction of metals is mainly attributed to the metabolites of the TCA cycle.

Molecular Docking Evaluation of Some Natural Phenolic Compounds as Aldose Reductase Inhibitors for Diabetic Complications

The enzyme aldose reductase (AR) is a member of aldoketoreductase super-family which catalyzes the formation of sorbitol from glucose through polyol pathway of glucose catabolism. Reduced sorbitol production via polyol pathway due to AR inhibition is a target of choice for controlling major complications of diabetes. Epalrestat is the only commercially available inhibitor of AR till date,thus, there is a great need to search for more economical, nontoxic and safer inhibitors of AR enzyme. Flavonoids, the polyphenol compounds in plants have been reported for inhibitory effects against AR. The objective of this study is to explore the binding modes of natural phenolic compounds with AR to design safer natural drugs as alternatives to synthetic drugs. We conducted a molecular docking study on some natural phenolic compounds with AR enzyme in complex with the synthetic inhibitor. The overlay of the docked pose of the selected natural phenols with the ARreference inhibitor complex showed that the selected natural compounds have the similar binding pattern with the active site residues of the enzyme as that of co-crystallized inhibitor. The results of docking study showed the best binding affinity of AR with that of 2-(4-hydroxy-3-methoxyphenyl) ethanoic acid and butein, having the lowest binding free energy of –9.8 kcal/mol and–9.7 kcal/mol, respectively. This information can be utilized to design potent, economical and non-toxic natural AR inhibitors from natural phenols for the therapeutics of diabetic complications.

Activity of Catabolic Enzymes of Film-Forming Strains of <i>Staphylococcus aureus</i>

The activity of glucose catabolism pathways of staphylococci strains able to form biofilm and isolated from vagina of women with dysbiosis of reproductive tract and strains isolated from women without disorders of microflora was studied. It was established that the investigated film-forming strains utilized the carbohydrates by pentose phosphate pathway mainly, as indicated by 23-33% higher enzyme activity compare to strains isolated from healthy women. Instead strains, isolated from women without reproductive tract dysbiosis, have higher activity of glycolytic enzymes on 13-28%. The prevalence of glycolytic transformation of glucose by strains isolated from healthy women also indicates by the depression of glucose oxidation during action of monoiodinacetate – classical inhibitor of glycolysis. It inhibit glycolysis of strains isolated from healthy women more significant. It was established that oxidase activity of film-forming strains isolated from women with dysbiosis, increased over 40% during the use of basic substrates of citric acid cycle. These data indicate a general increase of catabolic activity of oxidative type of staphylococci isolated during vaginal dysbiosis and able to form biofilm.

Activity of Catabolic Enzymes of Film-Forming Strains of <i>Staphylococcus aureus</i>

The activity of glucose catabolism pathways of staphylococci strains able to form biofilm and isolated from vagina of women with dysbiosis of reproductive tract and strains isolated from women without disorders of microflora was studied. It was established that the investigated film-forming strains utilized the carbohydrates by pentose phosphate pathway mainly, as indicated by 23-33% higher enzyme activity compare to strains isolated from healthy women. Instead strains, isolated from women without reproductive tract dysbiosis, have higher activity of glycolytic enzymes on 13-28%. The prevalence of glycolytic transformation of glucose by strains isolated from healthy women also indicates by the depression of glucose oxidation during action of monoiodinacetate – classical inhibitor of glycolysis. It inhibit glycolysis of strains isolated from healthy women more significant. It was established that oxidase activity of film-forming strains isolated from women with dysbiosis, increased over 40% during the use of basic substrates of citric acid cycle. These data indicate a general increase of catabolic activity of oxidative type of staphylococci isolated during vaginal dysbiosis and able to form biofilm.

Metabolic engineering and adaptive evolution ofEscherichia coliKO11 for ethanol production through the Entner-Doudoroff and the pentose phosphate pathways

BACKGROUND Ethanologenic Escherichia coli KO11 was modified to channel carbon flux from glucose through the Entner–Doudoroff (ED-P) and pentose phosphate (PP-P) pathways by using a phosphoglucose isomerase (pgi) knockout in the glycolytic pathway. This strain grows very slowly under non-aerated conditions with minimal media supplemented with 4% glucose. To improve the capacity to grow, KO11 Δpgi was evolved for 60 days; the resultant strain was named KO11 E35, which directs the carbon flux through the PP-P and ED-P to lactate and acetate production. RESULTS The activities of glucose-6-phosphate dehydrogenase and the ED-P enzymes increased 17-fold and 2-fold, respectively, in KO11 E35 in comparison with KO11. A homoethanologenic derivative was constructed from KO11 E35 by deleting the pta, ack and ldh genes, yielding the KO11 PPAL strain. This strain channels most of the carbon flux from pyruvate to ethanol and increased expression of heterologous pyruvate decarboxylase and alcohol dehydrogenase from Zymomonas mobilis allowed us to obtain specific ethanol production rates similar to those found in KO11, but with half the cell mass, i.e. larger ethanol/glucose and ethanol/biomass yields. CONCLUSIONS These results suggest that it is possible to obtain the same carbon flux using the PP-P and ED-P as when using the Embden–Meyerhof–Parnas pathway for glucose catabolism to ethanol. © 2016 Society of Chemical Industry

Establishing a synergetic carbon utilization mechanism for non-catabolic use of glucose in microbial synthesis of trehalose

In nature glucose is a common carbon and energy source for catabolic use and also a building unit of polysaccharides and glycosylated compounds. The presence of strong glucose catabolic pathways in microorganism rapidly decomposes glucose into smaller metabolites and challenges non-catabolic utilization of glucose as C6 building unit or precursor. To address this dilemma, we design a synergetic carbon utilization mechanism (SynCar), in which glucose catabolism is inactivated and a second carbon source (e.g. glycerol) is employed to maintain cell growth and rationally strengthen PEP driving force for glucose uptake and non-catabolic utilization. Remarkably, a trehalose biosynthesis model developed for proof-of-concept indicates that SynCar leads to 131% and 200% improvement in trehalose titer and yield, respectively. The conversion rate of glucose to trehalose reaches 91% of the theoretical maximum. This work demonstrates the broad applicability of SynCar in the biosynthesis of molecules derived from non-catabolic glucose.