High Acid Production Research Articles

Sugar Metabolism of Scardovia wiggsiae, a Novel Caries-Associated Bacterium.

Scardovia wiggsiae has been detected from caries in children and adolescents and has been suggested to be a caries-associated microorganism. To investigate the cariogenic potential of S. wiggsiae, we examined carbohydrate metabolism and acid productivity, the fluoride sensitivity of carbohydrate metabolism and the mechanism by which fluoride inhibits carbohydrate metabolism, and the acid sensitivity of carbohydrate metabolism in this bacterium. S. wiggsiae metabolized glucose and reduced the environmental pH to 3.5. It mainly produced acetic acid from glucose, together with small amounts of lactic and formic acid. The 50% inhibitory concentration of fluoride for acid production was 8.0 mM at pH 7.0 and 1.5 mM at pH 5.5, which were much higher than those of representative caries-associated bacteria, such as Streptococcus mutans. Metabolomic profiles showed the accumulation of 3-phosphoglycerate and a marked reduction in the pyruvate concentration in the presence of fluoride, suggesting that fluoride inhibits the latter half of glycolysis, including enolase activity. Enolase activity was inhibited by fluoride in S. wiggsiae, but it was more fluoride-tolerant than the enolase activity of S. mutans. Unlike in S. mutans, lactic acid did not inhibit acid production by S. wiggsiae at acidic pH. These results indicate that S. wiggsiae exhibits high acid production and tolerance to fluoride and lactic acid. S. wiggsiae possesses a unique metabolic pathway, the F6PPK shunt, which might allow it to avoid the lactate-formate pathway, including fluoride-sensitive enolase activity, and enable metabolic flow to the fluoride-tolerant acetate pathway. The fluoride tolerance of S. wiggsiae’s enolase activity also increases the fluoride tolerance of its carbohydrate metabolism. The lactic acid tolerance of S. wiggsiae’s acid production might result in S. wiggsiae having high acidogenic and aciduric potential and make it ecologically competitive in acidic environments, such as caries lesions, where lactic acid predominates.

High lactobionic acid production by immobilized Zymomonas mobilis cells: a great step for large-scale process.

Lactobionic acid and sorbitol are produced from lactose and fructose in reactions catalyzed by glucose-fructose oxidoreductase and glucono-δ-lactonase, periplasmic enzymes present in Zymomonas mobilis cells. Considering the previously established laboratory-scale process parameters, the bioproduction of lactobionic acid was explored to enable the transfer of this technology to the productive sector. Aspects such as pH, temperature, reuse and storage conditions of Ca-alginate immobilized Z. mobilis cells, and large-scale bioconversion were assessed. Greatest catalyst performance was observed between pH range of 6.4 and 6.8 and from 39 to 43°C. The immobilized biocatalyst was reused for twenty three 24-h batches preserving the enzymatic activity. The activity was maintained during biocatalyst storage for up to 120days. Statistically similar results, approximately 510mmol/L of lactobionic acid, were attained in bioconversion of 0.2 and 3.0L, indicating the potential of this technique of lactobionic acid production to be scaled up to the industrial level.

Metabolic engineering of an industrial Aspergillus niger strain for itaconic acid production

Itaconic acid is a value-added organic acid that is widely applied in industrial production. It can be converted from citric acid by some microorganisms including Aspergillus terreus and Aspergillus niger. Because of high citric acid production (more than 200g/L), A. niger strains may be developed into powerful itaconic acid-producing microbial cell factories. In this study, industrial citric acid-producing strain A. niger YX-1217, capable of producing 180.0-200.0g/L, was modified to produce itaconic acid by metabolic engineering. A key gene cadA encoding aconitase was expressed in A. niger YX-1217 under the control of three different promoters. Analyses showed that the PglaA promoter resulted in higher levels of gene expression than the PpkiA and PgpdA promoters. Moreover, the synthesis pathway of itaconic acid was extended by introducing the acoA gene, and the cadA gene, encoding aconitate decarboxylase, into A. niger YX-1217 under the function of the two rigid short-peptide linkers L1 or L2. The resulting recombinant strains L-1 and L-2 were induced to produce itaconic acid in fed-batch fermentations under three-stage control of agitation speed. After fermentation for 104h, itaconic acid concentrations in the recombinant strain L-2 culture reached 7.2g/L, which represented a 71.4% increase in itaconic acid concentration compared with strain Z-17 that only expresses cadA. Therefore, co-expression of acoA and cadA resulted in an extension of the citric acid metabolic pathway to the itaconic acid metabolic pathway, thereby increasing the production of itaconic acid by A. niger.

Morphological, Pathogenic and Toxigenic Variability in the Rice Sheath Rot Pathogen Sarocladium Oryzae.

Sheath rot is an emerging rice disease that leads to considerable yield losses. The main causal agent is the fungus Sarocladium oryzae. This pathogen is known to produce the toxins cerulenin and helvolic acid, but their role in pathogenicity has not been clearly established. S. oryzea isolates from different rice-producing regions can be grouped into three phylogenetic lineages. When grown in vitro, isolates from these lineages differed in growth rate, colour and in the ability to form sectors. A diverse selection of isolates from Rwanda and Nigeria, representing these lineages, were used to further study their pathogenicity and toxin production. Liquid chromatography high-resolution mass spectrometry analysis was used to measure cerulenin and helvolic acid production in vitro and in planta. The three lineages clearly differed in pathogenicity on the japonica cultivar Kitaake. Isolates from the least pathogenic lineage produced the highest levels of cerulenin in vitro. Helvolic acid production was not correlated with the lineage. Sectorisation was observed in isolates from the two least pathogenic lineages and resulted in a loss of helvolic acid production. In planta, only the production of helvolic acid, but not of cerulenin, correlated strongly with disease severity. The most pathogenic isolates all belonged to one lineage. They were phenotypically stable, shown by the lack of sectorisation, and therefore maintained high helvolic acid production in planta.

Conceptual design of water separation process in glycerol-based acrylic acid production

This paper focuses on the conceptual design of a quenching system to separate the water produced in a glycerol-based acrylic acid production process. In the glycerol-based process, acrylic acid is produced through fermentation and dehydration, and a large amount of water is generated. Thus, an effective way to separate water from acrylic acid is essential. We investigate a process scheme for quenching systems that separates the water generated from these reactions. The liquid–liquid extraction process is applied to separate water for high purity acrylic acid production. The selection of the solvent in extraction process is important so we compared several representative solvents, then results is that toluene is the most suitable solvent. As a result, a conceptual design using toluene as a solvent was suggested, and the proposed process using a quenching system to separate the water in two steps was investigated. The sensitivity analysis and economic assessment of the proposed process resulted in a 46.0 wt% reduction in the total flowrate of the subsequent processes, and reductions in the capital and operating costs by 52.0% and 39.3%, respectively.

Oxy-pressurized fluidized bed combustion: Configuration and options analysis

Bio-energy carbon capture and storage is a promising option to mitigate or eliminate CO2 emissions from fossil fuel-based heat, steam, and power generation. Among the different carbon capture technologies, oxy-fuel fluidized bed combustion is an attractive option due to its fuel flexibility and moderate operating temperature, making it suitable for bio-energy carbon capture and storage. A recent breakthrough in the development of this technology is operation under pressurized conditions. In order to assess the benefits of oxy-pressurized fluidized bed combustion, a number of design configurations and options were analyzed via process simulation. Three coals, one coke, and one torrefied hardwood biomass were selected for this work. A series of parameters, including reactor and system configuration, were varied to determine their impact on key performance metrics such as oxygen requirement, power balance, availability of high temperature heat, and by-product generation. The shift from coal to torrefied biomass only marginally affected the total amount of recoverable heat for power production, but resulted in significant reductions in both power and oxygen requirements. It was observed that an increase in operating pressure led to a higher amount of available heat due to the recovery of the latent heat of H2O condensation. An optimum operating pressure, ranging from 7 to 15 bar(g), was obtained when considering the total power consumed within the power plant. Results showed that the total quantity of recoverable high temperature heat is slightly higher for the circulating bed configuration in comparison to that of the bubbling. The use of a flue gas wet sulphuric acid process for sulphur removal resulted in the production of a high purity sulphuric acid product (>98 wt%) and increases in useable heat were noted at elevated pressures where total sulphur capture could be pushed to as high as 99.97%. Additionally, changes in flue gas O2 concentration via the wet sulphuric acid process and sorbent injection into the combustor were found to have significant impacts on process performance and natural gas/O2 demands.

Diet and Chronic Kidney Disease

Kidney disease affects almost 15% of the US population, and prevalence is anticipated to grow as the population ages and the obesity epidemic continues due to Western dietary practices. The densely caloric Western diet, characterized by high animal protein and low fruit and vegetable content, has fueled the growth of chronic diseases, including chronic kidney disease. The glomerulus or filtering unit of the kidney is very susceptible to barotrauma, and diets high in animal protein impede the glomerulus' ability to protect itself from hemodynamic injury. High animal protein intake combined with low intake of fruits and vegetables also leads to a high net endogenous acid production requiring augmentation of ammonium excretion in order to prevent acidosis. This higher workload of the kidney to maintain a normal serum bicarbonate level may further exacerbate kidney disease progression. This article reviews the potential mechanisms whereby several key characteristics of the typical Western diet may impact kidney disease incidence and progression. Reducing animal protein intake and egg yolk and increasing intake of fruits and vegetables and fiber may prevent or delay end-stage renal disease, but few clinical trials have examined vegetarian diets for management of chronic kidney disease. More research is needed to determine optimal dietary patterns for the prevention of kidney disease and its progression.

Life cycle assessment and multi-criteria analysis of sugarcane biorefinery scenarios: Finding a sustainable solution for the South African sugar industry

Abstract The valorisation of sugarcane lignocelluloses is a potential solution to ensure the sustainability of the South African sugar industry. The sustainability of six biorefinery scenarios were assessed and compared. The scenarios are: a CHP coal supplemented itaconic acid biorefinery (Scenario 1), bioenergy self-sufficient (ESS) itaconic acid biorefinery (Scenario 2), ESS polyhydroxybutyrate (PHB) biorefinery (Scenario 3), ESS succinic acid and PHB biorefinery (Scenario 4), ESS succinic acid biorefinery (Scenario 5) and a stand-alone CHP plant (Scenario 6). An environmental life cycle assessment (eLCA) was conducted to identify potential problem or ‘hot spot’ areas in the respective processes, and to compare the environmental impacts of the bio-products to one another, as well as to their fossil reference products. Carbon footprint and water scarcity impact were included as the two eLCA parameters, together with four life cycle costing (LCC) parameters and one social life assessment (sLCA) parameter, in a life cycle sustainability assessment (LCSA). The LCSA parameters were normalized and weighed in a multi-criteria decision analysis tool to determine the most sustainable solution for implementation by the South African sugar industry. It was found that a trade-off exists between the environmental and techno-economic performance. Scenario 4 is the most sustainable scenario due to the environmental advantage obtained by the high succinic acid production volume, since the environmental burden is shared across a large number of bioproduct units together with the economic advantage of a high PHB selling price, while being bioenergy self-sufficient.

Manganese Deficiency Is Required for High Itaconic Acid Production From D-Xylose in Aspergillus terreus.

Itaconic acid is used as a bio-based, renewable building block in the polymer industry. It is produced by submerged fermentations of the filamentous fungus Aspergillus terreus from molasses or starch, but research over the efficient utilization of non-food, lignocellulosic plant biomass is soaring. The objective of this study was to test whether the application of two key cultivation parameters for obtaining itaconic acid from D-glucose in high yields – Mn2+ ion deficiency and high concentration of the carbon source – would also occur on D-xylose, the principal monomer of lignocellulose. To this end, a carbon and energy balance for itaconic acid formation was established, which is 0.83 moles/mole D-xylose. The effect of Mn2+ ions on itaconic acid formation was indeed similar to that on D-glucose and maximal yields were obtained below 3 μg L–1 Mn2+ ions, which were, however, only 0.63 moles of itaconic acid per mole D-xylose. In contrast to the case on D-glucose, increasing D-xylose concentration over 50 g L–1 did not change the above yield. By-products such as xylitol and α-ketoglutarate were found, but in total they remained below 2% of the concentration of D-xylose. Mass balance of the fermentation with 110 g L–1 D-xylose revealed that >95% of the carbon from D-xylose was accounted as biomass, itaconic acid, and the carbon dioxide released in the last step of itaconic acid biosynthesis. Our data show that the efficiency of biomass formation is the critical parameter for itaconic acid yield from D-xylose under otherwise optimal conditions.

Optimization of Batch Dark Fermentation of Chlorella sp. Using Mixed-Cultures for Simultaneous Hydrogen and Butyric Acid Production

This paper reports on the optimum conditions for simultaneous hydrogen and butyric acid production from microalgae (Chlorella sp.) using enriched anaerobic mixed cultures as inoculum. The fermentation was objectively carried out under acidogenic conditions to achieve butyric acid for further ABE fermentation in solventogenesis stage. The main effects of initial pH (5 and 7), temperature (35 °C and 55 °C), and substrate concentration (40, 60, 80, and 100 g-VS/L) for hydrogen and butyric acid production were evaluated by using batch fermentation experiment. The major effects on hydrogen and butyric acid production are pH and temperature. The highest production of hydrogen and butyric acid was observed at pH 7 and temperature 35 °C. Using initial Chlorella sp. concentration of 80 g-VS/L or 100 g-VS/L at pH 7 and temperature 35 °C could produce hydrogen with an average yield of 22 mL-H2/g-VS along with high butyric acid production yield of 0.05 g/g-VS, suggesting that microalgae (Chlorella sp.) has potential to be converted directly to butyric acid by using acidogenesis under above optimum conditions.

Xylooligosaccharides as prebiotics from biomass autohydrolyzate

With an increased awareness of health and wellness, prebiotics have received a great amount of attention recently. In this study, autohydrolyzate from hot water treatment of Miscanthus lignocellulosic biomass was evaluated for its prebiotic effect by fermentation of Lactobacillus brevis strain. The cell growth on raw autohydrolyzate-supplemented media was comparable to the sample grown on glucose until an incubation time of 24 h then gradually declined. Autohydrolyzate contains various inhibitors (25.9% of total dissolved solids) and it was determined that dissolved lignin had a significant inhibitory effect to bacterial growth. When the autohydrolyzate was purified using a hydrophobic resin, purified autohydrolyzate exhibited high bacterial growth (cell density (OD 600) of 4.8) and high acid production (7.7 and 3.1 g/L of lactic and acetic acid, respectively), which was comparable with commercial xylooligosaccharides. In conclusion, mixed oligosaccharides in the autohydrolyzate from Miscanthus have considerable potential as a prebiotic and are comparable with commercial xylooligosaccharides derived products.

Influences of multiple clay minerals on the phosphorus transport driven by Aspergillus niger

Phosphorus (P) is a major limiting nutrient for plant growth. Clay minerals are able to work as active centers in soil system due to their high surface area and CEC. Yet, effects of clay minerals on P biogeochemical cycle driven by microorganisms are still unclear. In this study, hydroxylapatite and three typical clay minerals (kaolinite, palygorskite, and montmorillonite) were incubated with Aspergillus niger to investigate microbial influences on P release and adsorption. Due to the mineral particles, hyphae wrapped small montmorillonite particles (<10 μm, confirmed by SEM and TEM), which promoted microbial bioactivities, e.g., respiration and acid production. P consumption by the fungus lowered the available P from 143 to 68 ppm. Meanwhile, ATR-IR spectra and HPLC analysis confirmed the intense adsorption of oxalic acid (the primary microbial secretion) onto montmorillonite. Despite the higher acid production, both the high adsorption capability of the clay and the acid consumed by phosphate dissolution caused that pH values increased from ~2 to ~4 after montmorillonite addition. In contrast, low CEC, dispersibility, and surface area of kaolinite and palygorskite limited their ability to enhance microbial activities and the subsequent interactions with hyphae. Therefore, clay minerals, especially montmorillonite, can drive P transport with the favor from fungi in ecosystem.

Novel xanthine oxidase-based cell model using HK-2 cell for screening antihyperuricemic functional compounds

Hyperuricemia is a metabolic disease caused by disorders of purine metabolism, the prevalence of which has increased worldwide. Here, a cell model for high uric acid production was established in vitro employing cultured human kidney cells (HK-2 cells), and its molecular basis was analyzed using gene expression profile. High performance liquid chromatography (HPLC) was used to monitor the content of metabolites in cell culture media. Adenosine addition was found to induce HK-2 cells to produce uric acid precursors (inosine and hypoxanthine). Furthermore, the cell model was verified by confirming the antihyperuricemic effect of the widely used antihyperuricemic drugs allopurinol, probenecid, and febuxostat, as well as reported bioactive peptides and amino acids, encompassing glutathione, tryptophan and carnosine, which significantly reduced uric acid production in the HK-2 cells (p < 0.05). RNA-Seq technology was used to perform a wide transcriptome analysis of the hyperuricemic cell model, and the results demonstrated that it has the potential to be used as a rapid and valid in vitro model to screen antihyperuricemic compounds that mimics in vivo cell growth patterns.

Improving vanadium extraction from stone coal via combination of blank roasting and bioleaching by ARTP-mutated Bacillus mucilaginosus

Abstract In order to improve leaching efficiency of vanadium from stone coal, the combination of blank roasting and bioleaching using Bacillus mucilaginosus (B. mucilaginosus) mutants was evaluated. The atmospheric and room temperature plasma (ARTP) technique was used to generate B. mucilaginosus mutants. The results showed that a mutant B. mucilaginosus BM-50, after ARTP irradiation for 50 s, had the highest acid production. The total content of the organic acid produced by B. mucilaginosus BM-50 was nearly doubled compared with the wild strain after 2 days. After 20 days, vanadium leaching rate with B. mucilaginosus BM-50 reached 18.2%, which was improved compared with the original bacteria (15.3%). A pretreatment via blank roasting for stone coal further improved the vanadium dissolution by bioleaching, namely, 68.3% vanadium was extracted, which was much higher than that without blank roasting. It is shown that bioleaching by bacterial mutants by ARTP irradiation combined with blank roasting has great potential for improving vanadium recovery from low-grade vanadium bearing stone coal.

Leaching of nickel and vanadium from the spent fluid catalytic cracking catalyst by reconnoitering the potential of Aspergillus niger associating with chemical leaching

The current study evaluates the bio-potential of Aspergillus niger to leach out Nickel, Vanadium from spent fluid catalytic cracking catalyst (SFCCC) and is compared with chemical leaching by organic and inorganic acids. Bioleaching efficiency of Nickel at 1, 3 and 5% pulp densities were 16.5, 13 and 8% respectively. The percentage Vanadium leaching at same pulp densities was found to be 55, 37 and 27% respectively. Leaching efficiency decreased with increase in pulp density which may be due to the toxic effects of metals present in the SFCCC. The spent medium bioleaching resulted in 4.7% Nickel and 18% Vanadium leaching, which is far less than one step bioleaching (OSB). This may be attributed to high citric acid production (100 mM) in OSB which perhaps be triggered by key metals of SFCCC. The acidic pH of the medium suggests acidolysis as the principal leaching mechanism. Oxalic acid was found to be the dominant leaching agent for Nickel, while for Vanadium, OSB took over. The leaching of Nickel was found to be only due to predominant acids produced by Aspergillus niger. Biogenically produced leaching agents apart from predominant acids accounted for 40% of Vanadium leaching. It is evident that removal of volatile carbonaceous material from SFCCC improved Nickel leaching by three folds.

Improvement of kojic acid production in Aspergillus oryzae AR-47 mutant strain by combined mutagenesis.

Kojic acid is a kind of secondary metabolites, whose biosynthesis pathway remains unclear to date. It is produced industrially by microbial fermentation, and thus, mutagenesis breeding still plays a vital role for obtaining strains with high kojic acid production. The starting strain KA-11 isolated from mildewed fruits was identified as Aspergillus oryzae and then subjected to a combined mutagenesis program including microwave mutagenesis, UV irradiation, heat-LiCl, atmospheric, and room temperature plasma (ARTP). The kojic acid production was increased by 47.0%, 87.1%, 126.2%, and 292.3% compared with the starting strain KA-11 after each mutagenesis stage. A mutant strain AR-47 with kojic acid production of 96.5g/L in flask-shake fermentation was finally obtained. The fermentation time also decreased from 7 to 5 days. Real-time quantitative PCR was used to determine the transcriptional expression levels of genes that may be relevant to kojic acid biosynthesis, including kojA, kojR, kojT, AO090113000141, AO090113000143, AO090113000145, nrtA, and laeA. The results showed that the transcriptional expression levels of all these genes in high yield strain AR-47 had increased compared with the starting strain KA-11.

Changes in volatile and non-volatile compounds of model kimchi through fermentation by lactic acid bacteria

We analyzed the quality characteristics of model kimchi fermented with lactic acid bacteria (LAB; Leuconostoc mesenteroides, Leuconostoc citreum, Lactobacillus plantarum, Lactobacillus sakei, Weissella cibaria, and Weissella koreensis). The model kimchi was heat-treated at 60 °C for 10 min and then inoculated with different LAB strains. The fermentation process was performed at 15 °C for 48 h. Volatile and non-volatile flavour compounds, cell growth, pH, and sensory properties were monitored during fermentation. The pH decreased rapidly in kimchi fermented with L. mesenteroides, L. citreum, and L. plantarum along with high sugar utilization and acid production. The flavour profile of model kimchi varied with different LAB starter cultures. The sensory preference was higher when acetic acid and lactic acid were produced at the same time. There are significant positive correlations between overall preference and acetic acid (0.880), mannitol (0.871), and diallyl sulfide (0.863) concentrations. Principle component analysis (PCA) score plots showed clear differences in the metabolites of kimchi according to the LAB starter culture used in fermentation. Therefore, the type and concentration of metabolites present in kimchi are greatly affected by strain of LAB and fermentation time.

Prediction and Remediation of Water Quality in Monitoring Potential of Acid Mine Drainage

Acid Mine Drainage (AMD) associated with both active and abandoned mining operations related to sulfide minerals, oxidation of pyrite affording an acidic solution that contains toxic metal ions. Result shows that pH value of water in Kg. Aur, Chini and Sg. Lembing are acidic with value of 2.81, 4.16 and 3.60 respectively. Maximum concentrations of heavy metals in the study area are: Pb (0.2 mg/L), Cd (0.05 mg/L), Zn (5.1 mg/L), Cu (5.2 mg/L), Mn (10.9 mg/L), Cr (0.2 mg/L), Ni (0.2 mg/L), As (0.005 mg/L) and Fe (202.69 mg/L). Prediction of acid formation using acid-base calculations from all samples shows high potential acid production between 22.84-2500.16 kg CaCO3/tonne. The ratio of Neutralization (NP) with Acid Potential (APP) shows a very low value (ratio<1) Sg. Lembing (0.02), Chini (0.08), Selinsing (0.31) and Kg. Aur (0.81). Analysis from the tank experiment after 30 days shows pH of LFS, bentonite, activated carbon and zeolite change to 6.11, 3.91, 2.98 and 2.71 respectively. Three mine sites experiencing AMD are Kg. Aur, Chini and Sg. Lembing. Active neutralization treatment successfully shows LFS has great potential to control AMD based on their ability to neutralize the pH and remove heavy metals in the mine water. Meanwhile, the second adsorbent material is bentonite followed by activated carbon and zeolite.

Production of Added-Value Chemical Compounds through Bioconversions of Olive-Mill Wastewaters Blended with Crude Glycerol by a Yarrowia lipolytica Strain.

Olive mill wastewaters (OMW) are the major effluent deriving from olive oil production and are considered as one of the most challenging agro-industrial wastes to treat. Crude glycerol is the main by-product of alcoholic beverage and oleochemical production activities including biodiesel production. The tremendous quantities of glycerol produced worldwide represent a serious environmental challenge. The aim of this study was to assess the ability of Yarrowia lipolytica strain ACA-DC 5029 to grow on nitrogen-limited submerged shake-flask cultures, in crude glycerol and OMW blends as well as in media with high initial glycerol concentration and produce biomass, cellular lipids, citric acid and polyols. The rationale of using such blends was the dilution of concentrated glycerol by OMW to (partially or fully) replace process tap water with a wastewater stream. The strain presented satisfactory growth in blends; citric acid production was not affected by OMW addition (Citmax~37.0 g/L, YCit/Glol~0.55 g/g) and microbial oil accumulation raised proportionally to OMW addition (Lmax~2.0 g/L, YL/X~20% w/w). Partial removal of color (~30%) and phenolic compounds (~10% w/w) of the blended media occurred. In media with high glycerol concentration, a shift towards erythritol production was noted (Erymax~66.0 g/L, YEry/Glol~0.39 g/g) simultaneously with high amounts of produced citric acid (Citmax~79.0 g/L, YCit/Glol~0.46 g/g). Fatty acid analysis of microbial lipids demonstrated that OMW addition in blended media and in excess carbon media with high glycerol concentration favored oleic acid production.

Chlorogenic acid-mediated chemical defence of plants against insect herbivores.

Chlorogenic acid is one of the most abundant beneficial polyphenols in plants and is well known as a nutritional antioxidant in plant-based foods. Apart from its dietary antioxidant activity, it has been proved to be an efficient defence molecule against a broad range of insect herbivores. In the last two decades, several reports have shown the effectiveness of chlorogenic acid in insect growth deterrence. The pathway for chlorogenic acid biosynthesis in plants was previously elucidated, and metabolic engineering of the principal pathway showed high chlorogenic acid production in tomato plants. Herbivore-mediated induction of chlorogenic acid biosynthesis was also demonstrated both at metabolite and transcript level, although herbivore-mediated molecular regulation of chlorogenic acid biosynthesis is not yet fully elucidated. In this communication, we present our views on the efficacy of chlorogenic acid as an anti-herbivore defence molecule in plants and also discuss its future outlook.