Hexose Monophosphate Pathway Research Articles

Ficus carica Linn leaves extract induces cucumber resistance to Podosphaera xanthii by inhibiting conidia and regulating enzyme activity

Cucumbers (Cucumis sativus L.) are highly susceptible to infection by powdery mildew (PM), resulting in a deterioration of cucumber quality. The utilization of chemical control measures can effectively control cucumber PM; however, it may potentially give rise to issues such as environmental pollution, compromised safety, and drug resistance. The urgent need for a green, secure, and efficient strategy to manage cucumber PM necessitates attention. The predominant fungal pathogen causing PM in cucumbers is Podosphaera xanthii (P. xanthii) in this study. The preventive and control efficacy of Ficus carica Linn leaf extract (FLE) against P. xanthii was investigated for the first time. The preventive experiments entail pre-infection spraying of FLE prior to the occurrence of P. xanthii, while the curative experiments involve post-outbreak spraying of FLE. After comprehensive consideration, the optimal approach was determined to be spraying the front of cucumber leaves with a concentration of 0.04 mg/mL FLE in order to effectively control P. xanthii in leaf disc bioassay. The lowest superposition rate from FLE and trisodium phosphate dodecahydrate was 12.86 %, indicating that the impact of FLE on the respiratory metabolism of P. xanthii conidia primarily operates through the hexose monophosphate pathway (HMP). The growth of P. xanthii conidia and mycelium can be inhibited or delayed by FLE. The application of FLE can effectively mitigated chlorophyll loss, suppressed the activities of peroxidase (POD) and polyphenol oxidase (PPO), as well as enhanced the activities of phenylalanine ammonia lyase (PAL), chitinase, and β- 1,3-glucanase. Furthermore, three representative enzyme genes, PAL, POD, and chitinase, were chosen for the purpose of validation. The results suggested that FLE has the ability to modulate the expression of relevant enzyme genes, with peak effects observed after 3–4 days of treatment. The findings offer theoretical support for the advancement of novel botanical pesticides aimed at controlling crop diseases.

Whole-Genome Analysis of Novacetimonas cocois and the Effects of Carbon Sources on Synthesis of Bacterial Cellulose

Novacetimonas cocois WE7 (formally named Komagataeibacter cocois WE7) is a strain isolated from contaminated coconut milk, capable of producing bacterial cellulose (BC). We sequenced its genome to investigate why WE7 cannot synthesize BC from glucose efficiently. It contains about 3.5 Mb and six plasmid DNAs. N. cocois WE7 contains two bcs operons (bacterial cellulose operon, bcs I and bcs II); the absence of bcs III operons may lead to reduced BC production. From genome predictions, glucose, sucrose, fructose, maltose, and glycerol can be utilized to generate BC, with WE7 unable to metabolize carbohydrate carbon sources through the Embden–Meyerhof–Parnas (EMP) pathway, but rather through the Hexose Monophosphate Pathway (HMP) and tricarboxylic acid (TCA) pathways. It has a complete gluconic acid production pathway, suggesting that BC yield might be very low when glucose, maltose, and trehalose are used as carbon sources. This study represents the first genome analysis of N. cocois. This information is crucial for understanding BC production and regulation mechanisms in N. cocois and lays a foundation for constructing engineered strains tailored for diverse BC application purposes.

Enhanced Ribonucleic Acid Production by High-Throughput Screening Based on Fluorescence Activation and Transcriptomic-Guided Fermentation Optimization in Saccharomyces cerevisiae.

Currently, the primary source of ribonucleic acids (RNAs), which is used as a flavor enhancer and nutritional supplement in the food manufacturing and processing industries, for large-scale industrial production is yeast, where the challenge is to optimize the cellular RNA content. Here, we developed and screened yeast strains yielding abundant RNAs via various methods. The novel Saccharomyces cerevisiae strain H1 with a 45.1% higher cellular RNA content than its FX-2 parent was successfully generated. Comparative transcriptomic analysis elucidated the molecular mechanisms underlying RNA accumulation in H1. Upregulation of genes encoding the hexose monophosphate and sulfur-containing amino acid biosynthesis pathways promoted RNA accumulation in the yeast, particularly in the presence of glucose as the sole carbon source. Feeding methionine into the bioreactor resulted in 145.2 mg/g dry cell weight and 9.6 g/L of cellular RNA content, which is the highest volumetric productivity of RNAs achieved in S. cerevisiae. This strategy of breeding S. cerevisiae strain with a higher capacity of accumulating abundant RNAs did not employ any genetic modification and thus will be favored by the food industry.

Uncovering acid resistance genes in lactic acid bacteria and impact of non-viable bacteria on bacterial community during Chinese strong-flavor baijiu fermentation

Chinese strong-flavor baijiu (CSFB) brewing is a spontaneously solid-state fermentation process for approximately 60 days. Numerous microorganisms grow, die, and spark a series of metabolic reactions during fermentation. In this study, the microbial community and structure between total and viable bacteria in zaopei from the 5- and 20-year pits of CSFB are revealed by amplicon sequencing. Metagenome sequencing was applied to investigate acid resistance genes in Lactobacillus and predict carbohydrate active enzyme in zaopei. Besides, SourceTracker was conducted to expose bacterial sources. Results revealed that there was no significant difference in the bacterial community and structure between the total and viable bacteria; Lactobacillus was the most dominant bacterium in zaopei of two types of pits. Meanwhile, acid resistance genes argR, aspA, ilvE, gshA, DnaK, and cfa were genes that sustained Lactobacillus survival in the late stages of fermentation with high contents of acid and ethanol, and glycosyltransferases were identified as the predominated enzymes during the CSFB fermentation which catalyzed the process of lactic acid generation via Embden-Meyerhof-Parnas pathway and Hexose Monophosphate Pathway. Moreover, the environment contributed most bacteria to zaopei of the 5- and 20-year pits. These findings will provide a deeper understanding of the microbial community structure of viable and total bacteria and the reason for the dominance of Lactobacillus in the later stages of CSFB fermentation.

Antibacterial mechanisms of star anise essential oil microcapsules encapsulated by rice protein-depolymerized pectin electrostatic complexation and its application in crab meatballs

A mixed solid matrix of the depolymerized pectin (DP) and rice protein (RP) were investigated to improve the antibacterial activity of star anise essential oil (SAEO) through microencapsulation. The encapsulation was undertaken via electrostatic complexation method followed by spray drying. Under the optimized conditions, SAEO microcapsules with 92.2 % encapsulation efficiency was acquired at 3:2 of DP-to-RP, 1:3 of DP-to-SAEO and pH 4.0. DP-RP/SAEO microcapsules exhibited a spherical-shaped particle with smaller particle size, and sustained release. FTIR and morphology analysis confirmed that SAEO was successfully encapsulated in the solid matrix of microcapsules. DP-RP/SAEO microcapsules caused the destruction of cytomembranes and reduction of membrane proteins, which led to the alteration of cell membrane fluidity and integrity. Meanwhile, DP-RP/SAEO microcapsules repressed the key enzyme in tricarboxylic acid (TCA) and Hexose monophosphate pathway (HMP) cycle pathway of E. coli, S. aureus. The application experiments indicated DP-RP/SAEO microcapsules can effectively control the growth of E. coli and S. aureus in crab meatballs.

Oxidative stress markers as early predictors of diabetes complications in Type 2 diabetic patients

Objectives: Type 2 diabetes mellitus (T2DM) is a complex disease that affects many organs. Oxidative stress plays a key role in the pathogenesis of insulin resistance and β-cell dysfunction. Thus, the present study aimed to use oxidative stress markers as early predictors for the progression of diabetic complications. Materials and Methods: The study sample included 400 individuals (300 T2DM and 100 non-diabetic controls) aged from 35 to 59 years randomly selected from the outpatient clinic of the National Institute for Diabetes and Endocrinology. T2DM patients were divided into subgroups: Subgroup (1) patients without any complications, Subgroup (2) patients with diabetic nephropathy (DN) and Subgroup (3) patients with cardiovascular disorders (CVD). Biochemical markers of fasting blood glucose, glycated haemoglobin (HbA1C), glucose-6-phosphate dehydrogenase (G6PD), lactate, arginase, heme oxygenase-1 (HO-1), haemoglobin (Hb), triglycerides (TG), cholesterol, low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), urea, creatinine, malondialdehyde (MDA), reduced glutathione (GSH), catalase (CAT) and nitric oxide (NO) were performed. Results: DM patients showed significant increases in body mass index, systolic blood pressure, diastolic blood pressure, FBS, HbA1C, cholesterol, TG, LDL-C and glomerular filtration rate, while HDL-C decreased. Significant increases were observed in HO-1, MDA and NO, while G6PD/lactate, GSH and CAT decreased in DM patients. The DN and CVD patients exhibited a significant increase in HO-1, MDA and NO; while G6PD/lactate, GSH and CAT decreased compared with DM patients. Receiver operating characteristic analysis showed that the sensitivity and specificity of oxidative stress markers were 66.67–100%. Conclusion: Hexose monophosphate (HMP)/glycolysis pathways are shifted during DM near glycolysis rather than HMP pathway to produce energy where the amount of glucose enters the cells is low, causing oxidative stress. Oxidative stress markers could be used as early predictors of diabetes complications.

Synergistic antibacterial mechanism of different essential oils and their effect on quality attributes of ready-to-eat pakchoi (Brassica campestris L. ssp. chinensis)

The mixture of garlic essential oil (GEO), ginger essential oil (GIEO) and litsea cubeba essential oil (LCEO) was prepared and its effect on the antibacterial activity of E. coli, S. aureus and P. aeruginosa, as well as properties of ready-to-eat pakchoi during storage were assessed. GEO, GIEO or LCEO treatment significantly enhanced the accumulation of reactive oxygen species (ROS) levels, resulting in disruption of the permeability of cell membrane, the leakage of cytoplasmic contents, and the alteration of the secondary structure of bacterial proteins. Meanwhile, GEO, GIEO or LCEO treatment repressed the key enzyme in tricarboxylic acid (TCA) and Hexose monophosphate pathway (HMP) cycle of E. coli, S. aureus and P. aeruginosa. Essential oil treatments (p < 0.05) could significantly prolong the shelf life of pakchoi, total bacterial count (TBC) values and chlorophyll content of GEO/GIEO/LCEO sample were 3.47 log cfu/g and 0.82 mg/g, respectively, after storage for 7 days. E. coli, S. aureus and P. aeruginosa counts in GEO/GIEO/LCEO samples decreased by 56.76 %, 70.10 %, 73.95 % compared to CK (no essential oil) samples. The comprehensive results from the sensory (flavor and color) and microbial analysis (especially TBC) showed that GEO/GIEO/LCEO could extend the shelf life of ready-to-eat pakchoi from 4 d to 7 d. As compared with GEO, GIEO or LCEO individually, the combination of GEO, GIEO and LCEO exhibited synergistic effect and more pronouncedly antibacterial activity to improve quality of ready-to-eat pakchoi.

Antibacterial mechanisms of Orostachys cartilaginous cell cultures: effect on cell permeability and respiratory metabolism of Bacillus subtilis

Orostachys cartilaginous of Crassulaceae family is a plant native to the Changbai Mountain area, China. Although O. cartilaginous has various medicinal values, its product development and production are restricted by the insufficient resource available. O. cartilaginous cell cultures possess an efficient antibacterial effect against Bacillus subtilis, but the underlying mechanism is not clear yet. Therefore, this study investigated the effects of extract from bioreactor cultured O. cartilaginous cells (OE) on B. subtilis cell permeability and respiratory metabolism to provide a reference for the further utilization of O. cartilaginous cell cultures. Results showed alkaline phosphatase activity, electrical conductivity, nucleic acid and protein contents in B. subtilis suspensions were significantly increased (p < 0.01) by OE treatment, indicating the occurrence of cell damage or increase in cell permeability. OE inhibited B. subtilis respiration, and the combination groups of OE + iodoacetic acid (IA) and OE + sodium phosphate (SP) showed low superposition rates (approximately 35 %), revealing that OE likely affected IA- and SP-represented metabolic pathways. The activities of B. subtilis enzymes, specifically, hexokinase and pyruvate kinase in the embden-meyerhof-parnas (EMP) pathway and glucose-6-phosphate dehydrogenase in the hexose monophosphate (HMP) pathway, decreased after OE treatment. This result proved that OE inhibited B. subtilis respiration by regulating the EMP and HMP pathways.

Effects of seasonal temperature variations on phosphorus removal, recovery, and key metabolic pathways in the suspended biofilm

The effects of seasonal temperature variations on phosphorus removal performance and community structure of dominant polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) were explored. Such impacts on the dominance of PAOs and GAOs involved in carbon and phosphorus metabolic pathways and gene abundance of key enzymes in biofilm sequencing batch reactor (BSBR) were studied. Enzyme assay and Miseq high-throughput sequencing revealed that typical GAOs hold a competitive advantage, the activities of phosphate kinase (PPK) and phosphate hydrolase (PPX) were decreased, and typical GAOs deteriorated phosphorus removal performance in summer (27–30 °C). In spring, autumn, and winter (15–22 °C), PAOs dominated the competitive advantage, the activities of PPK and PPX were increased, and atypical PAOs dominated the improvement of phosphorus removal performance. Metagenomic sequencing showed that the reducing power of PAOs for polyhydroxyalkanoate ( PHA) synthesis mainly came from the glycolysis pathway, followed by hexose monophosphate pathway (HMP) and tricarboxylic acid (TCA) cycles. The change of phosphorus removal performance was not only related to the carbon and phosphorus metabolic pathways activated by PAOs, but also closely associated with the change of the competitive pathways between GAOs and PAOs. Collectively, our findings provided a temperature reference for the improvement of BSBR process performance and added the first in-depth information for the understanding of the phosphorus removal mechanism and the competition mechanism with GAOs in BSBR.

Quantifying dynamic range in red blood cell energetics: Evidence of progressive energy failure during storage.

During storage, red blood cells (RBCs) undergo significant biochemical and morphologic changes, referred to collectively as the "storage lesion". It was hypothesized that these defects may arise from disrupted oxygen-based regulation of RBC energy metabolism, with resultant depowering of intrinsic antioxidant systems. As a function of storage duration, the dynamic range in RBC metabolic response to three models of biochemical oxidant stress (methylene blue, hypoxanthine/xanthine oxidase, and diamide) was assessed, comparing glycolytic flux by NMR and UHPLC-MS methodologies. Blood was processed/stored under standard conditions (AS-1 additive solution) with leukoreduction. Over a 6-week period, RBC metabolic and antioxidant status were assessed at baseline and following exposure to the three biochemical oxidant models. Comparison was made of glycolytic flux (1 H-NMR tracking of [2-13 C]-glucose and metabolomic phenotyping with [1,2,3-13 C3 ] glucose), reducing equivalent (NADPH/NADP+ ) recycling, and thiol-based (GSH/GSSG) antioxidant status. As a function of storage duration, we observed the following: (1) a reduction in baseline hexose monophosphate pathway (HMP) flux, the sole pathway responsible for the regeneration of the essential reducing equivalent NADPH; with (2) diminished stress-based dynamic range in both overall glycolytic as well as proportional HMP flux. In addition, progressive with storage duration, RBCs showed (3) constraint in reducing equivalent (NADPH) recycling capacity, (4) loss of thiol based (GSH) recycling capacity, and (5) dysregulation of metabolon assembly at the cytoplasmic domain of Band 3 membrane protein (cdB3). Blood storage disturbs normal RBC metabolic control, depowering antioxidant capacity and enhancing vulnerability to oxidative injury.

Controlled-release casein/cinnamon essential oil nanospheres for the inactivation of Campylobacter jejuni in duck

Campylobacter jejuni (C. jejuni) is one of the most common foodborne pathogens that cause human sickness mostly through the poultry food chain. Cinnamon essential oil (CEO) has excellent antibacterial ability against C. jejuni growth. This study investigated the antibacterial mechanism of CEO against C. jejuni primarily through metabolism, energy metabolism of essential enzymes (AKPase, β-galactosidase, and ATPase), and respiration metabolism. Results showed that the hexose monophosphate pathway (HMP) was inhibited, and that the enzyme activity of G6DPH substantially decreased upon treatment with CEO. Analysis of the effect of CEO on the expression of toxic genes was performed by the real-time PCR (RT-PCR). The expression levels of the toxic genes cadF, ciaB, fliA, and racR under CEO treatment were determined. Casein/CEO nanospheres were further prepared for the effective inhibition of C. jejuni and characterized by particle-size distribution, zeta-potential distribution, fluorescence, TEM, and GC–MS methods. Finally, the efficiency of CEO and casein/CEO nanospheres in terms of antibacterial activity against C. jejuni was verified. The casein/CEO nanospheres displayed high antibacterial activity on duck samples. The population of the test group decreased from 4.30 logCFU/g to 0.86 logCFU/g and 4.30 logCFU/g to 2.46 logCFU/g at 4 °C and at 25 °C for C. jejuni, respectively. Sensory evaluation and texture analysis were also conducted on various duck samples.

Effect of dithiocyano-methane on hexose monophosphate pathway in the respiratory metabolism of Escherichia coli

This paper studied the inhibitory effects of dithiocyano-methane (DM) on the glucose decomposition pathway in the respiratory metabolism of Escherichia coli. We investigated the effects of DM on the activities of key enzymes (ATPase and glucose-6-phosphate dehydrogenase, G6PDH), the levels of key product (nicotinamide adenosine denucleotide hydro-phosphoric acid, NADPH), and gene expression in the hexose monophosphate pathway (HMP). The results showed that the minimum inhibitory concentration (MIC) and the minimum bactericide concentration (MBC) of DM against the tested strains were 5.86 mg/L and 11.72 mg/L, respectively. Bacteria exposed to DM at MIC demonstrated an increase in bacterial ATPase and G6PDH activities, NADPH levels, and gene expression in the HMP pathway compared to bacteria in the control group, which could be interpreted as a behavioral response to stress introduced by DM. However, DM at a lethal concentration of 10 × MIC affected glucose decomposition by inhibiting mainly the HMP pathway in E. coli.

Extract from Oenothera biennis L. stalks efficiently inhibits Staphylococcus aureus activity by affecting cell permeability and respiratory metabolism

Current studies on Oenothera biennis L. have focused on seeds rather than on stalks. Thus, information on the bioactive effects of O. biennis stalks is lacking. Therefore, this study investigated the antibacterial effect of O. biennis stalk extract (OBSE) and its underlying mechanisms against Staphylococcus aureus in terms of cell permeability and respiration metabolism to effectively utilize O. biennis stalks. Results showed that OBSE inhibited S. aureus growth. The diameter of the inhibitory zone reached 13.57 mm, and the minimum inhibitory concentration was 1 mg/mL. The activity of alkaline phosphatase and the levels of electronic conductivity, nucleic acid, and protein in S. aureus suspension were remarkably decreased (p < 0.01) by OBSE treatment because of the leakage of cell contents. Furthermore, OBSE inhibited S. aureus respiration. The superposition rate of OBSE and trisodium phosphate was the lowest, and the activity of glucose-6-phosphate dehydrogenase was obviously decreased (p < 0.01) by OBSE treatment. Thus, OBSE was involved in regulating the hexose monophosphate pathway. Consequently, O. biennis stalks have a potential application in antibacterial products.

Downregulated Recycling Process but Not De Novo Synthesis of Glutathione Limits Antioxidant Capacity of Erythrocytes in Hypoxia.

Red blood cells (RBCs) are susceptible to sustained free radical damage during circulation, while the changes of antioxidant capacity and regulatory mechanism of RBCs under different oxygen gradients remain unclear. Here, we investigated the changes of oxidative damage and antioxidant capacity of RBCs in different oxygen gradients and identified the underlying mechanisms using an in vitro model of the hypoxanthine/xanthine oxidase (HX/XO) system. In the present study, we reported that the hypoxic RBCs showed much higher oxidative stress injury and lower antioxidant capacity compared with normoxic RBCs. In addition, we found that the disturbance of the recycling process, but not de novo synthesis of glutathione (GSH), accounted for the significantly decreased antioxidant capacity of hypoxic RBCs compared to normoxic RBCs. We further elucidated the underlying molecular mechanism by which oxidative phosphorylation of Band 3 blocked the hexose monophosphate pathway (HMP) and decreased NADPH production aggravating the dysfunction of GSH synthesis in hypoxic RBCs under oxidative conditions.

Physiological function analysis of Lactobacillus plantarum Y44 based on genotypic and phenotypic characteristics

In our previous studies, Lactobacillus plantarum Y44 showed antioxidant activity and favorable gastric and intestinal transit tolerance. In the current study, we investigated the physiological function of L. plantarum Y44 based on an analysis of its genotype and phenotype. The complete genome of L. plantarum Y44 contained a single circular chromosome of 3,255,555 bp, with a GC content of 44.6%, and a single circular plasmid of 51,167 bp, with a GC content of 38.8%. The L. plantarum Y44 genome contained 3,293 genes including 3,112 protein coding sequences, 16 rRNAs, 66 tRNAs, 4 small (s)RNAs, and 95 pseudo genes. Lactobacillus plantarum Y44 could metabolize 24 different carbohydrate sources. Nineteen complete phosphoenolpyruvate-dependent sugar phosphotransferase system complex genes and intact Embden-Meyerhof-Parnas pathway and hexose monophosphate pathway enzyme genes, as well as abundant carbohydrate active enzyme genes, were identified in the L. plantarum Y44 genome. We also identified genes related to the biosynthesis of exopolysaccharide and surface proteins. Surface proteins played an important role in the L. plantarum Y44 adhesion to HT-29 cell monolayers, as evidenced by the removal of cell surface proteins leading to decreased adhesion capacity. The L. plantarum Y44 genome contained genes encoding chaperones, intracellular proteases, and 2-component systems, which were associated with the general stress response. Genes encoding bile salt hydrolase, F0F1-ATPase, Na+/H+-antiporter, H+/Cl- exchange transporter, cyclopropane-fatty acyl-phospholipid synthase, and alkaline shock protein were identified in the L. plantarum Y44 genome, which might explain the strain's favorable gastric and intestinal transit tolerance. Some genes associated with encoding the NADH system, glutathione system, and thioredoxin system were predicted via in silico analysis and might account for the strain's ability to scavenge reactive oxygen species. Lactobacillus plantarum Y44 was susceptive to 7 antibiotics and did not produce biogenic amines, likely due to the absence of acquired antibiotic resistance genes and amino acid decarboxylase genes. The phenotype profile of L. plantarum Y44 was associated with its genetic characteristics, indicating that strains with certain physiological functions can be screened by analyzing their phenotypic and genotypic characteristics. Lactobacillus plantarum Y44 has the potential to be used as a starter culture in fermented dairy products.

Oplopanax elatus adventitious root production through fed-batch culture and their anti-bacterial effects

Fed-batch culture (FBC) is extensively used in microbial culture to achieve a high yield of the desired products. However, the FBC application is less in plant cells or organs because of relatively complex chemical components in the culture medium. To develop the FBC of adventitious roots (ARs) of Oplopanax elatus, the present study designed two FBC systems, where the initial culture media were controlled as 3 L of half- (FBC1) and full-strength (FBC2) of Murashige and Skoog medium, and the culture efficiency was compared with the batch culture (BC). The result showed that AR biomass and bioactive compound accumulation were favorable in both FBC systems compared with those in the BC system. Between FBC1 and FBC2, a significant difference was exerted, with the former showing a good culture efficiency, and 5381.6 mg l−1 of total polysaccharides and 950.8 mg l−1 of total flavonoids were produced in FBC1. In addition, the anti-bacterial property of O. elatus ARs was evaluated for their further using in the production of relative products. The extract from FBC1-cultured ARs (OAE) inhibited growth of bacteria including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis, and a higher anti-bacterial effect was found on E. coli. Consequently, the effects of OAE on cell permeability and oxidative respiratory metabolism of E. coli were investigated. The levels of alkaline phosphatase activity, nucleotide or protein leakage, and electrical conductivity in the bacterial substrate were increased by the OAE treatment, illustrating that OAE changed the permeability of cell membranes or walls of E. coli. Simultaneously, OAE inhibited the respiratory of E. coli and a low superposition rate (30.5%) was found in the combination group of OAE with sodium phosphate. Furthermore, the activity of the key enzyme (glucose-6-phosphate dehydrogenase) in the hexose monophosphate (HMP) pathway was obviously decreased by the OAE treatment, confirming that OAE exerts its anti-bacterial effect on E. coli by regulating the HMP pathway. Fed-batch culture improves culture efficiency of Oplopanax elatus adventitious roots. Large amounts of polysaccharides and flavonoids were produced in fed-batch culture. Adventitious roots possessed higher anti-bacterial effect against Escherichia coli. Cell permeability of Escherichia coli were changed by treatments of adventitious root extracts. Extracts inhibited respiratory of Escherichia coli by affecting hexose monophophate pathway.

Antibacterial mechanism of Tetrapleura tetraptera extract against Escherichia coli and Staphylococcus aureus and its application in pork

AbstractThe antibacterial activity and the mechanism of Tetrapleura tetraptera root extract against Escherichia coli and Staphylococcus aureus were investigated. The mechanism of action of T. tetraptera on tested bacterial species was predominantly characterized by the study of transmission electron microscopy, which revealed severe damage on the primary target which affected the cell integrity and cell membrane permeability. The loss of soluble proteins studied by bacterial protein sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis and the decreased adenosine triphosphate and DNA contents confirmed the leakage of cell wall. In addition, the studies revealed that the root extract of T. tetraptera could also disrupt the respiratory metabolism by inhibiting the bacteria through the Embden–Meyerhof–Parnas and the hexose monophosphate pathways. T. tetraptera extract possessed a high level of antimicrobial activity in pork, which significantly reduced total viable bacterial population. This study clearly indicates that the T. tetraptera could be a potential source of new antimicrobial agent which has proven effective activity against antibiotic‐resistant strains of pathogens.Practical ApplicationsTetrapleura tetraptera is a flowering plant native to Africa with a wide range of applicability in local cuisines and traditional medicine. The T. tetraptera root extract possesses high antimicrobial activity against both gram‐positive and gram‐negative bacteria. This study could contribute to the better understanding of antibacterial mechanism of T. tetraptera. As a natural food preservative, it has broad prospect to be utilized in the meat industry.

Inactivation mechanism of E. coli O157:H7 under ultrasonic sterilization.

Ultrasonic sterilization (US), as a promising non-thermal sterilization method, exhibits unique superiorities than traditional sterilization methods. In this study, the inactivation mechanism of E. coli O157:H7 under US was investigated in cucumber and bitter gourd vegetable juices. Results revealed that the US treatment showed good antibacterial ability in countering E. coli O157:H7. Through determinations of conductivity and β-galactosidase activity, significant augmentation in membrane permeability of the bacteria was confirmed after the US treatment. The morphologies of the US treated E. coli O157:H7 demonstrated that the integrity of the cell membrane was disrupted by US treatment. SDS-PAGE and LSCM data further proved the disruptive action of US, leading to the leakage of proteins and DNA through the breakage on cell membrane. The decrease of metabolic-related enzyme activity was verified through investigation of bacterial metabolism. The antibacterial mechanism analysis indicated that the US can generate free radicals which resulted in the rise of intracellular oxidative stress, attenuation of energy metabolism and inhibition of hexose monophosphate pathway. As the application verification, the US treatment can cause the deprivation of E. coli O157:H7 cell viability in vegetable juices without obvious impact on the sensory quality.

Diversity and Succession of Microbiota during Fermentation of the Traditional Indian Food Idli.

Idli, a naturally fermented Indian food, is prepared from a mixture of rice and black gram (lentil). To understand its microbial community during fermentation, detailed analysis of the structural and functional dynamics of the idli microbiome was performed by culture-dependent and -independent approaches. The bacterial diversity and microbial succession were assessed at different times of fermentation by 16S rRNA amplicon sequencing. Results highlighted that most microbiota belonged to phylum Firmicutes (70%) and Proteobacteria (22%). Denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR) analysis confirmed the diversity and succession involved therein. A culture-dependent approach revealed that the microbially diverse populations were conserved across different geographical locations. The fermentation was primarily driven by lactic acid bacteria as they constitute 86% of the total bacterial population, and genus Weissella emerged as the most important organism in fermentation. The natural microbiota of the grains mainly drives the fermentation, as surface sterilized grains did not show any fermentation. Growth kinetics of idli microbiota and physicochemical parameters corroborated the changes in microbial dynamics, acid production, and leavening occurring during fermentation. Using a metagenomic prediction tool, we found that the major metabolic activities of these microbial fermenters were augmented during the important phase of fermentation. The involvement of the heterofermentative hexose monophosphate (HMP) pathway in batter leavening was substantiated by radiolabeled carbon dioxide generated from d-[1-14C]-glucose. Hydrolases degrading starch and phytins and the production of B vitamins were reported. Moreover, culturable isolates showing beneficial attributes, such as acid and bile tolerance, hydrophobicity, antibiotic sensitivity, and antimicrobial activity, suggest idli to be a potential dietary supplement.IMPORTANCE This is a comprehensive analysis of idli fermentation employing modern molecular tools which provided valuable information about the bacterial diversity enabling its fermentation. The study has demonstrated the relationship between the bacterial population and its functional role in the process. The nature of idli fermentation was found to be more complex than other food fermentations due to the succession of the bacterial population. Further studies using metatranscriptomics and metabolomics may enhance the understanding of this complex fermentation process. Moreover, the presence of microorganisms with beneficial properties plausibly makes idli a suitable functional food.

Hexose monophosphate shunt, the role of its metabolites and associated disorders: A review.

The hexose monophosphate (HMP) shunt actsas an essential component of cellular metabolism in maintaining carbon homeostasis. The HMP shunt comprises two phasesviz. oxidative and nonoxidative,which providedifferent intermediatesfor the synthesis of biomolecules like nucleotides, DNA, RNA, amino acids, and so forth; reducing molecules for anabolism and detoxifying the reactive oxygen species during oxidative stress. The HMP shunt is significantly important in the liver, adipose tissue, erythrocytes, adrenal glands, lactating mammary glands and testes. We have researched the articles related to the HMP pathway, its metabolites and disorders related to its metabolic abnormalities. The literature for this paper was taken typically from a personal database, the Cochrane database of systemic reviews, PubMed publications, biochemistry textbooks, and electronic journals uptildate on the hexose monophosphate shunt. The HMP shunt is a tightly controlled metabolic pathway, which is also interconnected with other metabolic pathways in the body like glycolysis, gluconeogenesis, and glucuronic acid depending upon the metabolic needs of the body and depending upon the biochemical demand. The HMP shunt plays a significant role in NADPH2 formation and in pentose sugars that are biosynthetic precursors of nucleic acids and amino acids. Cells can be protected from highly reactive oxygen species by NADPH 2 . Deficiency in the hexose monophosphate pathway is linked to numerous disorders. Furthermore, it was also reported that this metabolic pathway could act as a therapeutic target to treat different types of cancers, so treatments at the molecular level could be planned by limiting the synthesis of biomolecules required for proliferating cells provided by the HMP shunt, hence, more experiments still could be carried outto find additional discoveries.