Enhanced tolerance of Cupriavidus necator NCIMB 11599 to lignocellulosic derived inhibitors by inserting NAD salvage pathway genes.

Polyhydroxybutyrate (PHB) is a bio-based, biodegradable and biocompatible plastic that has the potential to replace petroleum-based plastics. Lignocellulosic biomass is a promising feedstock for industrial fermentation to produce bioproducts such as polyhydroxybutyrate (PHB). However, the pretreatment processes of lignocellulosic biomass lead to the generation of toxic byproducts, such as furfural, 5-HMF, vanillin, and acetate, which affect microbial growth and productivity. In this study, to reduce furfural toxicity during PHB production from lignocellulosic hydrolysates, we genetically engineered Cupriavidus necator NCIMB 11599, by inserting the nicotine amide salvage pathway genes pncB and nadE to increase the NAD(P)H pool. We found that the expression of pncB was the most effective in improving tolerance to inhibitors, cell growth, PHB production and sugar consumption rate. In addition, the engineered strain harboring pncB showed higher PHB production using lignocellulosic hydrolysates than the wild-type strain. Therefore, the application of NAD salvage pathway genes improves the tolerance of Cupriavidus necator to lignocellulosic-derived inhibitors and should be used to optimize PHB production.

Efficient succinic acid production from high-sugar-content beverages by Actinobacillus succinogenes.

This study presents the production of succinic acid (SA) by Actinobacillus succinogenes using high-sugar-content beverages (HSCBs) as feedstock. The aim of this study was the valorization of a by-product stream from the beverage industry for the production of an important building block chemical, such as SA. Three types of commercial beverages were investigated: fruit juices (pineapple and ace), syrups (almond), and soft drinks (cola and lemon). They contained mainly glucose, fructose, and sucrose at high concentration-between 50 and 1,000 g/L. The batch fermentation tests highlighted that A. succinogenes was able to grow on HSCBs supplemented with yeast extract, but also on the unsupplemented fruit juices. Indeed, the bacteria did not grow on the unsupplemented syrup and soft drinks because of the lack of indispensable nutrients. About 30-40 g/L of SA were obtained, depending on the type of HSCB, with yield ranging between 0.75 and 1.00 gSA /gS . The prehydrolysis step improved the fermentation performance: SA production was improved by 6-24%, depending on the HSCB, and sugar conversion was improved of about 30-50%.

Treatment with myo-inositol attenuates binding of the carbohydrate-responsive element-binding protein to the ChREBP-ß and FASN genes in rat nonalcoholic fatty liver induced by high-fructose diet.

Dietary supplementation with the major lipotrope myo-inositol (MI) potently reduces triglyceride (TG) content and expression levels of the fatty acid synthesis genes, for example, fatty acid synthase (FASN), in rat nonalcoholic fatty liver induced by high-fructose diet. Fatty acid synthesis genes are regulated by the carbohydrate-responsive element-binding protein (ChREBP) that exists in 2 isoforms: ChREBP-α and ChREBP-ß. The gene encoding the latter isoform is more responsive to fructose. Because MI repressed the induction of fatty acid synthesis gene expression by high-fructose diet, we hypothesized that MI may reduce binding of ChREBP to the carbohydrate response elements (ChoREs) in the ChREBP-ß gene as well as in fatty acid synthesis genes in the liver. Rats were fed high-glucose, high-fructose, or high-fructose diets supplemented with MI (0.05% and 0.25%) for 2 weeks. Hepatic TG content and expression levels of the glucose-6-phosphate dehydrogenase, malic enzyme 1, FASN, acetyl-CoA carboxylase alpha, S14, and ChREBP-ß were remarkably elevated in rats fed with high fructose compared with the corresponding levels in high-glucose group. Notably, elevated values of these parameters in high-fructose group were reduced by MI. Similarly, high-fructose-induced ChREBP binding to the ChoREs of the ChREBP-ß and FASN genes was nominally decreased by MI. This study showed that treatment with MI reduced elevated TG content and expression of genes related to fatty acid synthesis, such as FASN and ChREBP-ß, in rat nonalcoholic fatty liver induced by high-fructose diet. Furthermore, MI treatment nominally decreased increased binding of ChREBP to the ChoREs of ChREBP-ß and FASN genes.

Limiting Dietary Sugar Improves Pediatric Sinonasal Symptoms and Reduces Inflammation.

Excessive sugar consumption is associated with many chronic inflammatory diseases in adults. The effects of excessive sugar consumption in children have not been determined. In this study, we hypothesized that sinonasal symptoms and proinflammatory cytokine levels would be related and could be altered through reduction in sugar-sweetened beverage (SSB) consumption. To test this, we conducted a pilot study involving behavior modification and a 2-week follow-up. Seventeen children participants were recruited, and eleven completed the study. The experimental group presented with chronic nasal congestion or rhinorrhea defined by daily symptoms without acute illness for at least 3 months. The control group presented for non-nasal problems. Both groups received counseling to decrease SSB consumption. The Sinus and Nasal Quality of Life (SN-5) Survey was administered, and a blood sample was obtained by venipuncture at baseline and 2 weeks after counseling. Participants kept a 2-week food diary to document sugar intake. Serum lipid profile and inflammatory cytokines were measured. The experimental group reduced daily sugar intake, 46% versus 11% in the control. Baseline SN-5 scores were significantly worse in the experimental group and normalized to controls after intervention. Inflammatory cytokine levels were not different at baseline, but the experimental group significantly reduced in proinflammatory markers and increased the levels of anti-inflammatory markers after intervention. Our pilot data demonstrate higher sugar consumption may be associated with increased inflammatory stress and sinonasal symptoms. Reducing SSB and controlling inflammation in early childhood may have future health benefits.

Dietary copper-fructose interactions alter gut microbial activity in male rats.

Dietary copper-fructose interactions contribute to the development of nonalcoholic fatty liver disease (NAFLD). Gut microbiota play critical roles in the pathogenesis of NAFLD. The aim of this study was to determine the effect of different dietary doses of copper and their interactions with high fructose on gut microbiome. Male weanling Sprague-Dawley rats were fed diets with adequate copper (6 ppm CuA), marginal copper (1.5 ppm CuM) (low copper), or supplemented copper (20 ppm CuS) (high copper) for 4 wk. Deionized water or deionized water containing 30% fructose (wt/vol) was given ad libitum. Copper status, liver enzymes, gut barrier function, and gut microbiome were evaluated. Both low- and high-copper diets led to liver injury in high-fructose-fed rats, and this was associated with gut barrier dysfunction, as shown by the markedly decreased tight junction proteins and increased gut permeability. 16S rDNA sequencing analysis revealed distinct alterations of the gut microbiome associated with dietary low- and high-copper/high-fructose feeding. The common features of the alterations of the gut microbiome were the increased abundance of Firmicutes and the depletion of Akkermansia. However, they differed mainly within the phylum Firmicutes. Our data demonstrated that a complex interplay among host, microbes, and dietary copper-fructose interaction regulates gut microbial metabolic activity, which may contribute to the development of liver injury and hepatic steatosis. The distinct alterations of gut microbial activity, which were associated with the different dietary doses of copper and fructose, imply that separate mechanism(s) may be involved. NEW & NOTEWORTHY First, dietary low- and high-copper/high-fructose-induced liver injury are associated with distinct alterations of gut microbiome. Second, dietary copper level plays a critical role in maintaining the gut barrier integrity, likely by acting on the intestinal tight junction proteins and the protective commensal bacteria Akkermansia. Third, the alterations of gut microbiome induced by dietary low and high copper with or without fructose differ mainly within the phylum Firmicutes.

Neuroprotective effect of fermented papaya preparation by activation of Nrf2 pathway in astrocytes.

OBJECTIVES: Nuclear factor erythroid 2-related factor (Nrf2) in astrocyte plays important roles in brain homeostasis. Fermented papaya preparation (FPP) has anti-oxidative, anti-inflammatory, immunoregulatory properties. The present study investigated the effects of FPP on activation of Nrf2 and release of Nrf2-regulated neuroprotective antioxidants and detoxifying molecules. METHODS: Primary cultured astrocytes from rat embryos were treated with FPP for 6 or 24 hours. The expression levels of nuclear Nrf2 and cytoplasmic Nrf2-regulated molecules were determined by western blot analysis and immunohistochemistry. Glutathione levels were measured in cells and medium. Dopaminergic neurons were exposed 6-hydroxydopamine (6-OHDA) with/without pre-treatment with FPP astrocytes. Mice were treated orally with FPP for 2 weeks. RESULTS: FPP increased nuclear translocation of Nrf2 in striatal astrocytes, induced up-regulation of NAD(P)H quinine oxidoreductase-1, glutathione-S transferase and hemeoxygenase-1, and increased glutathione level and the percentage of metallothionein-expressing astrocytes. Moreover, FPP suppressed 6-OHDA-induced dopaminergic neuronal loss in not only neuron-astrocyte mixed culture, but also neuron-rich cultures pre-treated with glial conditioned medium. Two-week oral treatment of mice with FPP resulted in Nrf2 activation and increase in glutathione level in striatum. DISCUSSION: The results indicated that FPP enhances the anti-oxidative capacity through activation of Nrf2 in astrocytes, suggesting it may provide neuroprotection in oxidative stress-related neurodegenerative diseases.

Dietary sugars, not lipids, drive hypothalamic inflammation.

OBJECTIVE: The hypothalamus of hypercaloric diet-induced obese animals is featured by a significant increase of microglial reactivity and its associated cytokine production. However, the role of dietary components, in particular fat and carbohydrate, with respect to the hypothalamic inflammatory response and the consequent impact on hypothalamic control of energy homeostasis is yet not clear. METHODS: We dissected the different effects of high-carbohydrate high-fat (HCHF) diets and low-carbohydrate high-fat (LCHF) diets on hypothalamic inflammatory responses in neurons and non-neuronal cells and tested the hypothesis that HCHF diets induce hypothalamic inflammation via advanced glycation end-products (AGEs) using mice lacking advanced glycation end-products (AGEs) receptor (RAGE) and/or the activated leukocyte cell-adhesion molecule (ALCAM). RESULTS: We found that consumption of HCHF diets, but not of LCHF diets, increases microgliosis as well as the presence of N(ε)-(Carboxymethyl)-Lysine (CML), a major AGE, in POMC and NPY neurons of the arcuate nucleus. Neuron-secreted CML binds to both RAGE and ALCAM, which are expressed on endothelial cells, microglia, and pericytes. On a HCHF diet, mice lacking the RAGE and ALCAM genes displayed less microglial reactivity and less neovasculature formation in the hypothalamic ARC, and this was associated with significant improvements of metabolic disorders induced by the HCHF diet. CONCLUSIONS: Combined overconsumption of fat and sugar, but not the overconsumption of fat per se, leads to excessive CML production in hypothalamic neurons, which, in turn, stimulates hypothalamic inflammatory responses such as microgliosis and eventually leads to neuronal dysfunction in the control of energy metabolism.

Odd Chain Fatty Acids; New Insights of the Relationship Between the Gut Microbiota, Dietary Intake, Biosynthesis and Glucose Intolerance.

Recent findings have shown an inverse association between circulating C15:0/C17:0 fatty acids with disease risk, therefore, their origin needs to be determined to understanding their role in these pathologies. Through combinations of both animal and human intervention studies, we comprehensively investigated all possible contributions of these fatty acids from the gut-microbiota, the diet, and novel endogenous biosynthesis. Investigations included an intestinal germ-free study and a C15:0/C17:0 diet dose response study. Endogenous production was assessed through: a stearic acid infusion, phytol supplementation, and a Hacl1-/- mouse model. Two human dietary intervention studies were used to translate the results. Finally, a study comparing baseline C15:0/C17:0 with the prognosis of glucose intolerance. We found that circulating C15:0/C17:0 levels were not influenced by the gut-microbiota. The dose response study showed C15:0 had a linear response, however C17:0 was not directly correlated. The phytol supplementation only decreased C17:0. Stearic acid infusion only increased C17:0. Hacl1-/- only decreased C17:0. The glucose intolerance study showed only C17:0 correlated with prognosis. To summarise, circulating C15:0 and C17:0 are independently derived; C15:0 correlates directly with dietary intake, while C17:0 is substantially biosynthesized, therefore, they are not homologous in the aetiology of metabolic disease. Our findings emphasize the importance of the biosynthesis of C17:0 and recognizing its link with metabolic disease.