Blood glucose-lowering activity of protocatechuic acid is mediated by inhibiting a-glucosidase

α-Glucosidase inhibitors are effective in controlling postprandial hyperglycemia,which play crucial roles in the management of type 2 diabetes.Protocatechuic acid(PCA)is one of phenolic acids existing not only in various plant foods but also as a major microbial metabolite of dietary anthocyanins in the large colon.The present study investigated the inhibitory mechanism of PCA on a-glucosidase in vitro and examined its effect on postprandial blood glucose levels in vivo.Results from in vitro experiments demonstrated that PCA was a mix-type inhibitor of a-glucosidase.Driven by hydrogen bonds and van der Waals interactions,PCA reversibly bound withα-glucosidase to form a stable a-glucosidase-PCA complex in a spontaneous manner.The computational simulation found that PCA could insert into the active cavity of a-glucosidase and establish hydrogen bonds with catalytic amino acid residues.PCA binding aroused the steric hindrance for substrates to enter active sites and caused the structural changes of interacted catalytic amino acid residues.PCA also exhibited postprandial hypoglycemic capacity in diabetic mice.This study may provide the theoretical basis for the application of PCA as an active ingredient of functional foods in dietary management of diabetes.

Antioxidant,antimicrobial,and α-glucosidase inhibitory activities of saponin extracts from walnut(Juglans regia L.) leaves

Objective:To investigate the relationship between triterpenoid saponin content and antioxidant,antimicrobial,and α-glucosidase inhibitory activities of 70%ethanolic,butanolic,aqueous,supernate and precipitate extracts of Juglans regia leaves.Methods:Triterpenoid saponins of different Juglans regia leaf extracts were measured by the vanillin method.Antioxidant activity was evaluated against DPPH and ABTS free radicals.We also assessed α-glucosidase inhibitory and antimicrobial activities of the leaf extracts.Pearson’s correlation coefficient was evaluated to determine the correlation between the saponin content and biological activities.Results:The butanolic extract was most effective against DPPH with an IC50of 6.63μg/mL,while the aqueous extract showed the highest scavenging activity against ABTS free radical with an IC50of 42.27μg/mL.Pearson’s correlation analysis indicated a strong negative correlation (r=-0.956) between DPPH radical scavenging activity (IC50) and the saponin content in the samples examined.In addition,the aqueous extract showed the best α-glucosidase inhibitory activity compared with other extracts.All the extracts had fair antibacterial activity against Bacillus subtilis,Escherichia coli,and Klebsiella pneumoniae except for the aqueous extract.Conclusions:Juglans regia extracts show potent antioxidant,antimicrobial,and α-glucosidase inhibitory activities.There is a correlation between saponin levels in Juglans regia leaf extracts and the studied activities.However,additional research is required to establish these relationships by identifying the specific saponin molecules responsible for these activities and elucidating their mechanisms of action.

Selective leaching of lithium from spent lithium-ion batteries using sulfuric acid and oxalic acid

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries(LIBs)involve acid leaching to simultaneously extract all valuable metals into the leachate.These methods usually are followed by a series of separation steps such as precipitation,extraction,and stripping to separate the individual valuable metals.In this study,we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids.Under optimal leaching conditions(leaching time of 1.5 h,leaching temperature of 70°C,liquid-solid ratio of 4 mL/g,oxalic acid ratio of 1.3,and sulfuric acid ratio of 1.3),the lithium leaching efficiency reached89.6%,and the leaching efficiencies of Ni,Co,and Mn were 12.8%,6.5%,and 21.7%.X-ray diffraction(XRD)and inductively coupled plasma optical emission spectrometer(ICP-OES)analyses showed that most of the Ni,Co,and Mn in the raw material remained as solid residue oxides and oxalates.This study offers a new approach to enriching the relevant theory for selectively recovering lithium from spent LIBs.

Recovery of Li, Ni, Co and Mn from spent lithium-ion batteries assisted by organic acids: Process optimization and leaching mechanism

The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.

Structural characterizations andα-glucosidase inhibitory activities of four Lepidium meyenii polysaccharides with different molecular weights

Four polysaccharides(MCPa,MCPb,MCPc,MCPd)were obtained from Lepidium meyenii Walp.Their structures were characterized by chemical and instrumental methods including total sugar,uronic acid and protein content determi-nation,UV,IR and NMR spectroscopy,as well as monosaccharide composition determination and methylation analy-ses.Four polysaccharides were a group of glucans with different molecular weights ranging from 3.12 to 14.4 kDa,and shared a similar backbone chain consisting of(1→4)-glucose linkages with branches attached to C-3 and C-6.Furthermore,bioactivity assay showed that MCPs had concentration-dependent inhibitory activity onα-glucosidase.MCPb(Mw=10.1 kDa)and MCPc(Mw=5.62 kDa)with moderate molecular weights exhibited higher inhibitory activ-ity compared with MCPa and MCPd.

Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids

The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.

Endogenous biosynthesis of docosahexaenoic acid(DHA)regulates fish oocyte maturation by promoting pregnenolone production

Omega-3 polyunsaturated fatty acids(n-3 PUFAs),particularly docosahexaenoic acid(22:6n-3,DHA),play crucial roles in the reproductive health of vertebrates,including humans.Nevertheless,the underlying mechanism related to this phenomenon remains largely unknown.In this study,we employed two zebrafish genetic models,i.e.,elovl2^(-/-)mutant as an endogenous DHAdeficient model and fat1(omega-3 desaturase encoding gene)transgenic zebrafish as an endogenous DHA-rich model,to investigate the effects of DHA on oocyte maturation and quality.Results show that the elovl2^(-/-)mutants had much lower fecundity and poorer oocyte quality than the wild-type controls,while the fat1 zebrafish had higher fecundity and better oocyte quality than wildtype controls.DHA deficiency in elovl2^(-/-)embryos led to defects in egg activation,poor microtubule stability,and reduced pregnenolone levels.Further study revealed that DHA promoted pregnenolone synthesis by enhancing transcription of cyp11a1,which encodes the cholesterol side-chain cleavage enzyme,thereby stabilizing microtubule assembly during oogenesis.In turn,the hypothalamic-pituitary-gonadal axis was enhanced by DHA.In conclusion,using two unique genetic models,our findings demonstrate that endogenously synthesized DHA promotes oocyte maturation and quality by promoting pregnenolone production via transcriptional regulation of cyp11a1.

A comparison study on structure-function relationship of polysaccharides obtained from sea buckthorn berries using different methods:antioxidant and bile acid-binding capacity

In this study,the structural characters,antioxidant activities and bile acid-binding ability of sea buckthorn polysaccharides(HRPs)obtained by the commonly used hot water(HRP-W),pressurized hot water(HRP-H),ultrasonic(HRP-U),acid(HRP-C)and alkali(HRP-A)assisted extraction methods were investigated.The results demonstrated that extraction methods had significant effects on extraction yield,monosaccharide composition,molecular weight,particle size,triple-helical structure,and surface morphology of HRPs except for the major linkage bands.Thermogravimetric analysis showed that HRP-U with filamentous reticular microstructure exhibited better thermal stability.The HRP-A with the lowest molecular weight and highest arabinose content possessed the best antioxidant activities.Moreover,the rheological analysis indicated that HRPs with higher galacturonic acid content and molecular weight showed higher viscosity and stronger crosslinking network(HRP-C,HRP-W and HRP-U),which exhibited stronger bile acid binding capacity.The present findings provide scientific evidence in the preparation technology of sea buckthorn polysaccharides with good antioxidant and bile acid binding capacity which are related to the structure affected by the extraction methods.

Abiotic stress treatment reveals expansin like A gene OfEXLA1 improving salt and drought tolerance of Osmanthus fragrans by responding to abscisic acid

Sweet osmanthus(Osmanthus fragrans) is a having general approval aromatic tree in China that is widely applied to landscaping and gardening. However, the evergreen tree adaptability is limited by many environmental stresses. Currently, limited information is available regarding the genetic analysis and functional identification of expansin genes in response to abiotic stress in sweet osmanthus. In this study, a total of 29 expansin genes were identified and divided into four groups by genome-wide analysis from the sweet osmanthus genome. Transcriptome and quantitative Real-time PCR analysis showed that the cell wall-localized protein expansin-like A(OfEXLA1) gene was significantly induced by salt and drought treatment. Histochemical GUS staining of transgenic Arabidopsis lines in which GUS activity was driven with the OfEXLA1 promoter, GUS activity was significantly induced by salt, drought, and exogenous abscisic acid(ABA). In yeast, we found OfEXLA1overexpression significantly improved the population of cells compared with wild-type strains after NaCl and polyethylene glycol(PEG)treatment. Additionally, OfEXLA1 overexpression not only promoted plant growth, but also improved the salt and drought tolerance in Arabidopsis. To gain insight into the role of ABA signaling in the regulation of OfEXLA1 improving abiotic tolerance in sweet osmanthus, four differentially expressed ABA Insensitive 5(ABI5)-like genes(OfABL4, OfABL5, OfABL7, and OfABL8) were identified from transcriptome, and dualluciferase(dual-LUC) and yeast one hybrid(Y1H) assay showed that OfABL4 and OfABL5 might bind to OfEXLA1 promoter to accumulate the OfEXLA1 expression by responding to ABA signaling to improve abiotic tolerance in sweet osmanthus. These results provide the information for understanding the molecular functions of expansin-like A gene and molecular breeding of sweet osmanthus in future.

Ethanol extract of Annona muricata Linn fruit perform antidiabetic effect on type 2 diabetic mice through α-glucosidase inhibition

Objective:To explore the anti-diabetic effects and its underlying mechanism of Annona muricata Linn fruit ethanol extract(AME).Methods:Streptozotocin-induced type 2 diabetic(T2DM)mouse model was constructed.Those diabetic mice were randomly grouped and given 50 mg/kg acarbose or AME(200 mg/kg,100 mg/kg or 50 mg/kg)for four weeks.The body weight,postprandial blood glucose and glycosylated hemoglobin levels were measured during the administration.After the administration,a glucose tolerance test was performed,and the levels of triglycerides,cholesterol and low-density lipoproteins in mice were detected by biochemical test kits.The inhibitory activity of AME onα-glucosidase in vivo and in vitro was determined by enzyme inhibition tests.Results:AME significantly reduced weight gain,postprandial blood glucose,glycosylated hemoglobin and low-density lipoprotein levels in T2DM mice;enhanced glucose tolerance and pancreaticβ-cell function of T2DM mice;inhibitedα-glucosidase activity in mouse intestine in an noncompetitive manner.Conclusion:AME may noncompetitive inhibitα-glucosidase activity and reduce postprandial glucose intake to achieve a therapeutic and regulatory effect on type 2 diabetes.

Dietary supplementation of benzoic acid and essential oils combination enhances intestinal resilience against LPS stimulation in weaned piglets

Background The benefits of combining benzoic acid and essential oils(BAO)to mitigate intestinal impairment during the weaning process have been well established,while the detailed underlying mechanism has not been fully elucidated.Previous research has primarily focused on the reparative effects of BAO on intestinal injury,while neglecting its potential in enhancing intestinal stress resistance.Methods In this study,we investigated the pre-protective effect of BAO against LPS-induced stress using a modified experimental procedure.Piglets were pre-supplemented with BAO for 14 d,followed by a challenge with LPS or saline to collect blood and intestinal samples.Results Our findings demonstrated that BAO supplementation led to significant improvements in piglets’final weight,average daily gain,and feed intake/body gain ratio.Additionally,BAO supplementation positively influenced the composition of intestinal microbiota,increasing beneficial Actinobacteriota and Alloprevotella while reducing harmful Desulfobacterota,Prevotella and Oscillospira.Furthermore,BAO supplementation effectively mitigated oxidative disturbances and inflammatory responses induced by acute LPS challenge.This was evidenced by elevated levels of T-AOC,SOD,and GSH,as well as decreased levels of MDA,TNF-α,and IL-6 in the plasma.Moreover,piglets subjected to LPS challenge and pre-supplemented with BAO exhibited significant improvements in intestinal morphological structure and enhanced integrity,as indicated by restored expression levels of Occludin and Claudin-1 compared to the non-supplemented counterparts.Further analysis revealed that BAO supplementation enhanced the jejunal antioxidative capacity by increasing GSH-Px levels and decreasing MDA levels under the LPS challenge and stimulated the activation of the Nrf2 signaling pathway.Additionally,the reduction of TLR4/NF-κB/MAPK signaling pathways activation and proinflammatory factor were also observed in the jejunal of those piglets fed with BAO.Conclusions In summary,our study demonstrates that pre-supplementation of BAO enhances the anti-stress capacity of weaned piglets by improving intestinal microbiota composition,reinforcing the intestinal barrier,and enhancing antioxidative and anti-inflammatory capabilities.These effects are closely associated with the activation of Nrf2 and TLR4/NF-κB/MAPK signaling pathways.

Bile acids,gut microbiota,and therapeutic insights in hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is a prevalent and aggressive liver malignancy.The interplay between bile acids(BAs)and the gut microbiota has emerged as a critical factor in HCC development and progression.Under normal conditions,BA metabolism is tightly regulated through a bidirectional interplay between gut microorganisms and BAs.The gut microbiota plays a critical role in BA metabolism,and BAs are endogenous signaling molecules that help maintain liver and intestinal homeostasis.Of note,dysbiotic changes in the gut microbiota during pathogenesis and cancer development can disrupt BA homeostasis,thereby leading to liver inflammation and fibrosis,and ultimately contributing to HCC development.Therefore,understanding the intricate interplay between BAs and the gut microbiota is crucial for elucidating the mechanisms underlying hepatocarcinogenesis.In this review,we comprehensively explore the roles and functions of BA metabolism,with a focus on the interactions between BAs and gut microorganisms in HCC.Additionally,therapeutic strategies targeting BA metabolism and the gut microbiota are discussed,including the use of BA agonists/antagonists,probiotic/prebiotic and dietary interventions,fecal microbiota transplantation,and engineered bacteria.In summary,understanding the complex BA-microbiota crosstalk can provide valuable insights into HCC development and facilitate the development of innovative therapeutic approaches for liver malignancy.

Shikimic acid accelerates phase change and flowering in Chinese jujube

The juvenile-to-adult phase change with first flowering as the indicator plays a crucial role in the lifecycle of fruit trees. However, the molecular mechanisms underlying phase change in fruit trees remain largely unknown. Shikimic acid (ShA) pathway is a main metabolic pathway closely related to the synthesis of hormones and many important secondary metabolites participating in plant phase change. So,whether ShA regulates phase change in plants is worth clarifying. Here, the distinct morphological characteristics and the underlying mechanisms of phase change in jujube (Ziziphus jujuba Mill.), an important fruit tree native to China with nutritious fruit and outstanding tolerance abiotic stresses, were clarified. A combined transcriptome and metabolome analysis found that ShA is positively involved in jujube(Yuhong’×Xing 16’) phase change. The genes in the upstream of ShA synthesis pathway (ZjDAHPS, ZjDHQS and ZjSDH), the contents of ShA and the downstream secondary metabolites like phenols were significantly upregulated in the phase change period. Further, the treatment of spraying exogenous ShA verified that ShA at a very low concentration (60 mg·L^(-1)) can substantially speed up the phase change and flowering of jujube and other tested plants including Arabidopsis, tomato and wheat. The exogenous ShA (60 mg·L^(-1)) treatment in jujube seedlings could increase the accumulation of endogenous ShA, enhance leaf photosynthesis and the synthesis of phenols especially flavonoids and phenolic acids, and promote the expression of genes (ZjCOs, ZjNFYs and ZjPHYs) involved in flowering pathway. Basing on above results, we put forward a propose for the underlying mechanism of ShA regulating phase change, and a hypothesis that ShA could be considered a phytohormone-like substance because it is endogenous, ubiquitous, movable and highly efficient at very low concentrations. This study highlights the critical role of ShA in plant phase change and its phytohormone-like properties.

Gut microbiota induced abnormal amino acids and their correlation with diabetic retinopathy

AIM:To explore the correlation of gut microbiota and the metabolites with the progression of diabetic retinopathy(DR)and provide a novel strategy to elucidate the pathological mechanism of DR.METHODS:The fecal samples from 32 type 2 diabetes patients with proliferative retinopathy(PDR),23 with nonproliferative retinopathy(NPDR),27 without retinopathy(DM),and 29 from the sex-,age-and BMI-matched healthy controls(29 HC)were analyzed by 16S rDNA gene sequencing.Sixty fecal samples from PDR,DM,and HC groups were assayed by untargeted metabolomics.Fecal metabolites were measured using liquid chromatographymass spectrometry(LC-MS)analysis.Associations between gut microbiota and fecal metabolites were analyzed.RESULTS:A cluster of 2 microbiome and 12 metabolites accompanied with the severity of DR,and the close correlation of the disease progression with PDR-related microbiome and metabolites were found.To be specific,the structure of gut microbiota differed in four groups.Diversity and richness of gut microbiota were significantly lower in PDR and NPDR groups,than those in DM and HC groups.A cluster of microbiome enriched in PDR group,including Pseudomonas,Ruminococcaceae-UCG-002,Ruminococcaceae-UCG-005,Christensenellaceae-R-7,was observed.Functional analysis showed that the glucose and nicotinate degradations were significantly higher in PDR group than those in HC group.Arginine,serine,ornithine,and arachidonic acid were significantly enriched in PDR group,while proline was enriched in HC group.Functional analysis illustrated that arginine biosynthesis,lysine degradation,histidine catabolism,central carbon catabolism in cancer,D-arginine and D-ornithine catabolism were elevated in PDR group.Correlation analysis revealed that Ruminococcaceae-UCG-002 and Christensenellaceae-R-7 were positively associated with L-arginine,ornithine levels in fecal samples.CONCLUSION:This study elaborates the different microbiota structure in the gut from four groups.The relative abundance of Ruminococcaceae-UCG-002 and Parabacteroides are associated with the severity of DR.Amino acid and fatty acid catabolism is especially disordered in PDR group.This may help provide a novel diagnostic parameter for DR,especially PDR.

Elaidic acid leads to mitochondrial dysfunction via mitochondria-associated membranes triggers disruption of mitochondrial calcium fluxes

Elaidic acid(EA)stimulation can lead to endoplasmic reticulum stress(ERS),accompanied by a large release of Ca^(2+),and ultimately the activation of NLRP3 inflammasome in Kupffer cells(KCs).Mitochondrial instability or dysfunction may be the key stimulating factors to activate NLRP3 inflammasome,and sustained Ca^(2+)transfer can result in mitochondrial dysfunction.We focused on KCs to explore the damage to mitochondria by EA.After EA stimulation,cells produced an oxidative stress(OS)response with a significant increase in ROS release.Immunoprecipitation experiments and the addition of inhibitors revealed that the increase in the level of intracellular Ca^(2+)led to Ca^(2+)accumulation in the mitochondrial matrix via mitochondria-associated membranes(MAMs).This was accompanied by a significant release of m ROS,loss of MMP and ATP,and a significant increase in mitochondrial permeability transition pore opening,ultimately leading to mitochondrial instability.These findings confirmed the mechanism that EA induced mitochondrial Ca^(2+)imbalance in KCs via MAM,ultimately leading to mitochondrial dysfunction.Meanwhile,EA induced OS and the decrease of MMP and ATP in rat liver,and significant lesions were found in liver mitochondria.Swelling of the inner mitochondrial cristae and mitochondrial vacuolization occurred,with a marked increase in lipid droplets.

Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane electrolyzers.To dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but challenging.Herein,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from overoxidation.Simultaneously,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction barrier.As a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

Effect of different drying methods on the amino acids,α-dicarbonyls and volatile compounds of rape bee pollen

The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.

Metagenomic analysis revealing the metabolic role of microbial communities in the free amino acid biosynthesis of Monascus rice vinegar during fermentation

Free amino acid(FAA)is the important component of vinegar that infl uences quality perception and consumer acceptance.FAA is one of the major metabolites produced by microorganisms;however,the microbial metabolic network on FAA biosynthesis remains unclear.Through metagenomic analysis,this work aimed to elucidate the roles of microbes in FAA biosynthesis during Monascus rice vinegar fermentation.Taxonomic profiles from functional analyses showed 14 dominant genera with high contributions to the metabolism pathways.The metabolic network for FAA biosynthesis was then constructed,and the microbial distribution in different metabolic pathways was illuminated.The results revealed that 5 functional genera were closely involved in FAA biosynthesis.This study illuminated the metabolic roles of microorganisms in FAA biosynthesis and provided crucial insights into the functional attributes of microbiota in vinegar fermentation.

Antibacterial mechanism of kojic acid and tea polyphenols against Escherichia coli O157:H7 through transcriptomic analysis

Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.

Preparation of lactic acid bacteria compound starter cultures based on pasting properties and its improvement of glutinous rice flour and dough

The effects of 5 lactic acid bacteria(LAB)fermentation on the pasting properties of glutinous rice flour were compared,and suitable fermentation strains were selected based on the changes of viscosity,setback value,and breakdown value to prepare LAB compound starter cultures.The results revealed that Latilactobacillus sakei HSD004 and Lacticaseibacillus rhamnosus HSD005 had apparent advantages in increasing the viscosity and reducing the setback and breakdown values of glutinous rice flour.In particular,the compound starter created using the two abovementioned LAB in the ratio of 3:1 had better performance than that using a single LAB in improving the pasting properties and increasing the water and oil absorption capacity of glutinous rice flour.Moreover,the gelatinization enthalpy of the fermented samples increased significantly.For frozen glutinous rice dough stored for 28 days,the viscoelasticity of frozen dough prepared by compound starter was better than that of control dough,and the freezable water content was lower than that of control dough.These results indicate that compound LAB fermentation is a promising technology in the glutinous rice-based food processing industry,which has significance for its application.