Oxalic Acid Concentration Research Articles

Morphophysiological responses of red amaranth (Amaranthus tricolor L.) to osmopriming treatment to overcoming salinity stress

Global climate change induced environmental stress such as salinity significantly impact growth and crop productivity. Red amaranth (Amaranthus tricolor L.) is a vegetable commodity that has high nutritional value, but its productivity will decrease when grown in saline area. Seed priming is one of the pre-planting treatment techniques used to increase plant growth under unfavourable conditions. Osmopriming is one of the priming techniques where the seeds will be immersed in a solution with a high osmotic potential, such as PEG (Polyethylene Glycol). The purpose of this study was to determine the morphophysiological response of red amaranth to osmopriming treatment under salinity stress. Complete randomized design was used to arrange this experiment containing two variables including seed osmopriming (0, 5% and 10% of PEG) and salinity stress (0, 50, and 100 mM of NaCl). Morphophysiological parameters were measured including plant height, number of leaves, root length, leaf chlorophyll content, proline content, oxalic acid content and Ca-oxalate crystal density. After seed osmopriming with 10% of PEG 6000 increased plant height, number of leaves and root length of red amaranth Under salinity stress. Chlorophyll content increased while proline, oxalic acid content and Ca-oxalate crystal density decreased on osmopriming with 10% of PEG 6000. Seed osmopriming enhances morphophysiological characters to overcome problems in cultivating of red amaranth on saline area.

Shoot Nutrition and Flavor Variation in Two Phyllostachys Species: Does the Quality of Edible Bamboo Shoot Diaphragm and Flesh Differ?

For their quality evaluation, it is essential to determine both bamboo shoot nutrition and palatability, which will have a decisive effect on their economic value and market potential. However, differences in shoot nutrition and flavor variation among bamboo species, positions, and components have not been scientifically validated. This study assessed nutritional and flavor differences in two components (i.e., shoot flesh (BSF) and diaphragm (BSD)) of two Phyllostachys species (i.e., Phyllostachys edulis and Phyllostachys violascens) and analyzed any positional variation. Results showed that BSF protein, starch, fat, and vitamin C contents were comparatively higher. Nutrient compounds in the upper shoot segment of Ph. edulis were higher and contained less cellulose and lignin. However, both species' BSD total acid, oxalic acid, and tannin contents were comparable. BSD soluble sugar and sugar:acid ratio were higher than upper BSD total amino acid, four key amino acids (i.e., essential amino acid, bitter amino acid, umami amino acid, and sweet amino acid flavor compounds), and associated ratios were all higher than BSF while also being rich in amino acids. The content and proportion of BSF essential and bitter amino acid flavor compounds in Ph. edulis were high relative to Ph. violascens. Conversely, the content and proportion of BSD umami and sweet amino acid flavor compounds were comparable to that of Ph. edulis. Our results showed that bamboo shoot quality was affected by flavor compound differences and that interspecific and shoot components interact. This study offers a new perspective to determine the formative mechanisms involved in bamboo shoot quality while providing a basis for their different usages.

Recycling Strategy toward Efficient and Green Lithium Leaching from Coal-Based Lithium Ores Enabled by Solubility Engineering and Reusable Solid Acid

Lithium is an important strategic metal, but the supply of lithium ore is growing slowly, which is in sharp contradiction with the rapidly growing demand. Therefore, it is urgent to find new lithium resources. Recently, it has been found that coal-based lithium ore is expected to become a new type of lithium resource to meet the rapidly growing demand for lithium. However, the traditional Li extraction process using inorganic acids (i.e., H2SO4) is facing serious environmental issues, and the excess acid needs to be neutralized before the subsequent purification process. Herein, for the first time, we proposed a novel recycling strategy for the efficient and scalable Li leaching from coal-based Li ores with a reusable solid acid (oxalic acid), in which oxalic acid can be easily recovered after the leaching process with facile solubility engineering. The influences of the leaching conditions and oxalic acid concentration on the Li leaching and recycling rates of oxalic acid were explored in detail. Under the optimal conditions, the Li leaching rate (89.12%) and recovery rate (88.12%) of oxalic acid reached nearly 90%. In addition, the results of X-ray diffraction and Fourier-transform infrared clearly proved the high purity of the recovered oxalic acid after Li leaching, and the recovered oxalic acid also possessed excellent leaching performance after five times of recycling experiments. Moreover, the leaching kinetic analysis showed that the Li extraction from coal-based Li ore with oxalic acid was a chemical-controlled process with an activation energy (Ea) of 74.42 kJ/mol. Therefore, with solubility engineering, the recycling of oxalic acid after Li leaching could be easily realized, which is possible for other solid acids and provides a promising strategy for the simultaneous realization of green Li extraction and leaching acid recovery.

Averrhoa carambola leaves prevent dyslipidemia and oxidative stress in a rat model of poloxamer-407-induced acute hyperlipidemia.

Background: The star fruit [Averrhoa carambola L (Oxalidaceae)] is traditionally used in the treatment of many ailments in many countries. It possesses several pharmacological activities, including antioxidant and anti-inflammatory effects. However, it contains the neurotoxic caramboxin and its high content of oxalic acid limits its consumption by individuals with compromised kidney function. This study assessed the anti-hyperlipidemic and antioxidant activities of different fractions of the methanolic extract of A. carambola leaves (MEACL). Methods: The antioxidant activity was investigated using FRAP, and ABTS and DPPH radical-scavenging assays and the inhibitory activity toward pancreatic lipase (PL) and HMG-CoA reductase was assayed in vitro. Acute hyperlipidemia was induced by poloxamer-407 (P-407) in rats and different fractions of MEACL (n-hexane, chloroform, n-butanol, ethyl acetate (EA), water, and chloroform) were orally administered. Cholesterol and triglycerides were determined at 0, 12, 24, and 48h and LDL-C, vLDL-C, HDL-C, lipid peroxidation (LPO) and antioxidants were assayed after 48h. The expression of ABCA1, ABCG5, ABCG8, LDL-R, SREBP-1, and SREBP-2 and the activity of HMG-CoA reductase were assayed in the liver of P-407-administered rats treated with the EA fraction. Results: The in vitro data revealed potent radical-scavenging activities of MEACL fractions with the most potent effect showed by the EA fraction that also suppressed the activities of HMG-CoA reductase and PL. In P-407-induced hyperlipidemic rats, all fractions prevented dyslipidemia as shown by the decrease in total cholesterol, triglycerides, LDL-C, vLDL-C and atherogenic index. MEACL and its fractions prevented LPO and boosted GSH, superoxide dismutase, glutathione peroxidase, and catalase in P-407-administered rats. The EA fraction showed more effective anti-hyperlipidemic and antioxidant effects than other fractions and downregulated SREBP-2 while upregulated ABCA1 and LDL-R and ameliorated LPL and HMG-CoA reductase in hyperlipidemic rats. Conclusion: MEACL showed in vitro and in vivo antioxidant activity and the EA fraction significantly ameliorated dyslipidemia in a rat model of P-407-induced acute hyperlipidemia by modulating LPL, PL, HMG-CoA reductase, and cholesterolgenesis-related factors. Therefore, the leaves of A. carambola represent a safe alternative for the star fruit particularly in kidney disease patients, and the EA is the most effective anti-hyperlipidemic and antioxidant fraction.

Separation of Hydrochloric Acid and Oxalic Acid from Rare Earth Oxalic Acid Precipitation Mother Liquor by Electrodialysis.

In this study, the hydrochloric acid from rare earth oxalic acid precipitation mother liquor was separated by electrodialysis (ED) with different anion exchange membranes, including selective anion exchange membrane (SAEM), polymer alloy anion exchange membrane (PAAEM), and homogenous anion exchange membrane (HAEM). In addition to actual wastewater, nine types of simulated solutions with different concentrations of hydrochloric acid and oxalic acid were used in the experiments. The results indicated that the hydrochloric acid could be separated effectively by electrodialysis with SAEM from simulated and real rare earth oxalic acid precipitation mother liquor under the operating voltage 15 V and ampere 2.2 A, in which the hydrochloric acid obtained in the concentrate chamber of ED is of higher purity (>91.5%) generally. It was found that the separation effect of the two acids was related to the concentrations and molar ratios of hydrochloric acid and oxalic acid contained in their mixtures. The SEM images and ESD-mapping analyses indicated that membrane fouling appeared on the surface of ACS and CSE at the diluted side of the ED membrane stack when electrodialysis was used to treat the real rare earth oxalic acid precipitation mother liquor. Fe, Yb, Al, and Dy were found in the CSE membrane section, and organic compounds containing carbon and sulfur were attached to the surface of the ACS. The results also indicated that the real rare earth precipitation mother liquor needed to be pretreated before the separation of hydrochloric acid and oxalic acid by electrodialysis.

Response of Cd, Zn Translocation and Distribution to Organic Acids Heterogeneity in Brassica juncea L.

In order to investigate the translocation, distribution, and organic acid heterogeneity characteristics in Brassica juncea L., a pot experiment with the exogenous application of Cd and Zn was conducted to analyze the effects of Cd, Zn, and organic acid contents and heterogeneity on the translocation and distribution of Cd and Zn. The results showed that the Cd and Zn contents of B. juncea were mainly accumulated in the roots. The Cd content in the symplast sap was 127.66-146.50% higher than that in the apoplast sap, while the opposite was true for Zn. The distribution of Cd in xylem sap occupied 64.60% under 20 mg kg-1 Cd treatment, and Zn in xylem sap occupied 60.14% under 100 mg kg-1 Zn treatment. The Cd was predominantly distributed in the vacuole, but the Zn was predominantly distributed in the cell walls. In addition, oxalic and malic acids were present in high concentrations in B. juncea. In the vacuole, correlation analysis showed that the contents of Cd were negatively correlated with the contents of oxalic acid and succinic acid, and the contents of Zn were positively correlated with the contents of malic acid and acetic acid. The contents of Cd and Zn were negatively related to the contents of oxalic acid and citric acid in xylem sap. Therefore, Cd in B. juncea was mainly absorbed through the symplast pathway, and Zn was mainly absorbed through the apoplast pathway, and then Cd and Zn were distributed in the vacuole and cell walls. The Cd and Zn in B. juncea are transferred upward through the xylem and promoted by oxalic acid, malic acid, and citric acid.

Evaluation of oxalic acid with glycerin efficacy against Varroa destructor (Varroidae): a four year assay

Beekeepers in order to control the Varroa population, apply oxalic acid (OA) by trickling, spraying, evaporating, or fumigating, onto broodless colonies for higher efficacy. Recently, a new method was developed using strips with OA and glycerin during brood-rearing periods. However, there has been little research regarding the optimum concentration of the active ingredient and the suitable solvents to reach maximum efficacy. Thus, in the present study, we applied strips with different concentrations of OA in different mixtures of glycerin, assessed the efficacy of the method throughout a 4-year experiment, and compared it with others, commonly followed by beekeepers. Among the tested concentrations of OA, the optimum was 21% (w/v) (60 g OA, 130 mL glycerin, and 100 mL water), while the presence of water made the strips more manageable. The corrected efficacy of the method ranged from 90.4% to 94.5%, despite the different climate conditions prevailing each year and the presence of brood. All the tested concentrations presented a high number of fallen mites in the first 15–18 days, as glycerin releases OA slowly into the hive. On the other hand, synthetic acaricides or other methods (fumigation, essential oils) presented a corrected efficacy range from 10.1% to 85.6%, requiring more in some formulations repetitions. No bees’ toxicity was observed in all study cases. The results showed that the application of strips with 21% (w/v) OA diluted in glycerin and water seems to be more practical, leading to a successful Varroa control even in seasons with brood presence.

Determination of oxalic acid in herbal medicines by semi-micro hydrophilic interaction liquid chromatography coupled with electrochemical detection.

In this study, the determination of oxalic acid in herbal medicines was performed by using a hydrophilic interaction liquid chromatography coupled with electrochemical detection (HILIC-ECD) method. A semi-micro column packed with amide-silica particles and an acetonitrile-30mM phosphate buffer (pH 6.8) mixture (65:35, v/v) were used as the stationary and mobile phases, respectively, in the HILIC-ECD. A potential of + 1.1V vs. Ag/AgCl was applied to a glassy carbon working electrode. The ratio of the peak height of oxalic acid to that of the internal standard (synephrine) was proportional to the concentration of 0.45μg L-1 to 1.8mg L-1 with a correlation coefficient of 0.999. The detection limit (signal-to-noise ratio, S/N = 3) of oxalic acid was 0.17μg L-1. By the HILIC-ECD, the oxalic acid content in crude drugs and Kampo medicine extract granules (Zingiberis Rhizoma Processum, Pinelliae Tuber, Sho-seiryu-to, Hange-shashin-to, etc.) were determined with less than 2.9% relative standard deviation (RSD, n = 6), and their recoveries were more than 88.7% with less than 3.3% RSD (n = 6). In conclusion, we demonstrated that the HILIC-ECD performed measurements that were quite selective, accurate, and precise for the determination of oxalic acid in herbal medicines.

Seasonal Variations of Low-Molecular-Weight Organic Acids in Three Evergreen Broadleaf Rhododendron Forests.

Low-molecular-weight organic acids (LMWOAs) are widely distributed in forests. Fresh leaves, litter, humus, and the topsoil layer of representative Rhododendron delavayi (RD), Rhododendron agastum (RA), and Rhododendron irroratum (RI) in the Baili Rhododendron National Forest Park were sampled to explore their seasonal changes. The contents of oxalic, tartaric, malic, citric, acetic, lactic, succinic, and formic acids in samples from different seasons were determined by high-performance liquid chromatography. The results showed that the composition and content of the LMWOAs in the fresh leaves, litter, humus, and topsoil layer of the rhododendrons were affected by the tree species, samples, and season. The main LMWOA was oxalic acid (the average content in the samples was 195.31 µg/g), followed by malic acid (the average content in the samples was 68.55 µg/g) and tartaric acid (the average content in the samples was 59.82 µg/g). Succinic acid had the lowest content; the average content in the samples was 18.40 µg/g. The LMWOAs of the RD were the highest (the average content in the samples was 517.42 µg/g), and the LMWOAs of the RI were the lowest (the average content in the samples was 445.18 µg/g). The LMWOAs in the three rhododendron forests were in the order of fresh leaves > litter > humus > soil layers. This study showed the seasonal distribution characteristics of LMWOAs in three evergreen broadleaf rhododendron forests, and the results provide a reference for ecosystem management and the protection of wild rhododendron forests.

Comprehensive fruit quality assessment and identification of aroma-active compounds in green pepper (Capsicum annuum L.).

The wrinkled pepper (Capsicum annuum L.) is a type of chili pepper domesticated in northwestern China, with a characteristic flavor. Fifteen wrinkled and four smooth-skinned pepper varieties were evaluated for morphology, texture, color, nutrients, capsaicinoids, and volatile compounds at the mature fruit stage. The sensory evaluation showed wrinkled pepper was superior to smooth pepper in texture, and it has a highly significant correlation (p < 0.01) with cuticle thickness, maximum penetrating force, lignin content, and moisture content. Citric acid was the major organic acid in peppers, accounting for 39.10-63.55% of the total organic acids, followed by quininic acid. The average oxalic acid content of smooth peppers was 26.19% higher than that of wrinkled peppers. The pungency of wrinkled pepper fruits ranged from 1748.9 to 25529.4 SHU, which can be considered slightly to very spicy, while the four smooth varieties ranged between 866.63 and 8533.70 SHU, at slightly to moderately spicy. A total of 199 volatile compounds were detected in the 19 pepper varieties. The average volatile content of wrinkled pepper was 39.79% higher than that of smooth pepper. Twenty-nine volatile compounds, including 14 aldehydes, four alcohols, three esters, three ketones, two furans, one pyrazine, one acid, and one phenol, contributed to the fragrance of peppers and could be regarded as aroma-active compounds, with 2-isobutyl-3-methoxypyrazine being the major contributor among the 19 pepper varieties. Wrinkled pepper can be confidently distinguished from smooth pepper and is of superior quality. The current findings outlined the major texture-related characteristics of pepper as well as the main aroma-active compounds, providing valuable information for pepper quality breeding and consumer guidelines.

Impact of oxalate on the physicochemical properties of potato starch: An insight closely associated with Indian cuisine

Potato is one of the widely used vegetables in Indian cuisine. The starch of potato could undergo modification in presence of oxalic acid of tomato during cooking in Indian cuisine leading to the increased cooking time of potato. Present study analyses the effect of oxalic acid on the physicochemical properties of potato starch and investigate the reason behind the increased cooking time of potatoes in Indian food dishes. Water binding capacity, swelling power, solubility and paste clarity were determined for potato starch in the reaction mixture containing a varied concentration of oxalic acid. A significant increase in the water binding capacity and swelling power was observed on increasing the incubation temperature and concentration of oxalic acid. There was a sharp decline in the solubility of starch at higher temperatures and at 1 mg/mL oxalic acid concentration. The unexpected behaviour of solubility at a higher concentration of oxalic acid indicates that oxalic acid at 1 mg/mL alter the solubility of starch molecules in the bulk water. Treated starch showed high transmittance suggesting lesser opaqueness. Scanning Electron microscope results exhibited non-uniformity in starch granules with size varying from 5 μm to 50 μm. Most granules under Scanning Electron Microscope were smooth surfaces with few pores and defects.

Oxalic Acid Pretreatment on Enhancement of Enzymatic Saccharification from Napier Grass for Biofuel Production

Thailand as an agricultural country faces significant challenges in managing the abundant biomass waste generated from agricultural activities. Conventional disposal methods such as incineration contribute to pollution and limited availability of landfill space. To mitigate these issues valorization of this biomass waste has been a solution. This study focuses on the utilization of Napier grass as a renewable energy source. In this experiment, the Napier grass samples were pretreated using oxalic acid with temperature variations (50 – 100 °C), time (30 180 min), and oxalic acid concentration (2 10%w/v) to determine the limit of these three factors for optimization studies. The utilization of Box-Behnken Design (BBD) within Response Surface Methodology (RSM) enabled the determination of optimal pretreatment conditions and the exploration of the correlation between pretreatment factors and reducing sugar content. The model predicted pretreatment with an oxalic acid concentration of 6% w/v, pretreated at 100 °C for 105 min as the optimal pretreatment condition to produce a maximum reducing sugar concentration of 10.65 mg/ml. Therefore, the sample was pretreated at optimum conditions and the results revealed the amount of reducing sugar obtained was 10.67 mg/ml, which differed from the predicted value with an error of 0.22%. Thus, this study provides insight for future researchers on the optimum condition that can be applied for pretreating biomass with oxalic acid to maximize the sugar yield.

The potential of Robusta (Coffea canephora) green beans as a dentin hypersensitivity therapy agent: A review

Dentin hypersensitivity or sensitive teeth is one of the most disturbing diseases caused by the opening of the dentinal tubules which can transmit fluid to the pulp nerves of the tooth, so that patient feel a short and sharp pain when exposed to triggering agents. This can cause physical and psychological problems for the patient. In addition, it can have a negative impact on a person's quality of life, especially regarding food selection, plaque control methods, and aesthetic aspects. One of the treatments for dentine hypersensitivity is by using materials that contain a desensitizing effect, such as stannous, strontium, potassium, arginine, oxalate, and hydroxyapatite. These ingredients can be contained in toothpaste, serum, mouthwash and in dental office materials. Robusta green beans is known to contain fluoride and oxalic acid. Fluoride is needed by the teeth to prevent and repair porous teeth, cavities to hypersensitive teeth. While oxalic acid is a material that has a desensitizing effect, which can be used to treat dentine hypersensitivity. However, the content of oxalic acid and fluoride in Robusta green bean has not been studied further to determine its desensitization potential. This review article will discuss the possible desensitization potential of Robusta green bean.

Cloning, Expression Analysis, and Functional Characterization of Candidate Oxalate Transporter Genes of HbOT1 and HbOT2 from Rubber Tree (Hevea brasiliensis)

Secretion of oxalic acid from roots is an important aluminum detoxification mechanism for many plants such as Hevea brasiliensis (rubber tree). However, the underlying molecular mechanism and oxalate transporter genes in plants have not yet been reported. In this study, the oxalate transporter candidate genes HbOT1 and HbOT2 from the rubber tree were cloned and preliminarily identified. It was found that HbOT1 had a full length of 1163 bp with CDS size of 792 bp, encoding 263 amino acids, and HbOT2 had a full length of 1647 bp with a CDS region length of 840 bp, encoding 279 amino acid residues. HbOT1 and HbOT2 were both stable hydrophobic proteins with transmembrane structure and SNARE_assoc domains, possibly belonging to the SNARE_assoc subfamily proteins of the SNARE superfamily. qRT-PCR assays revealed that HbOT1 and HbOT2 were constitutively expressed in different tissues, with HbOT1 highly expressed in roots, stems, barks, and latex, while HbOT2 was highly expressed in latex. In addition, the expressions of HbOT1 and HbOT2 were up-regulated in response to aluminum stress, and they were inducible by metals, such as copper and manganese. Heterologous expression of HbOT1 and HbOT2 in the yeast mutant AD12345678 enhanced the tolerance to oxalic acid and high concentration aluminum stress, which was closely correlated with the secretion of oxalic acid. This study is the first report on oxalate transporter genes in plants, which provides a theoretical reference for the study on the molecular mechanism of oxalic acid secretion to relieve aluminum toxicity and on aluminum-tolerance genetic engineering breeding.

Phenolic, nutritional and molecular interaction study among different millet varieties

Millet varieties were analyzed for nutritional, antinutritional, mineral and phenolic profiles. Inhibition potential of phenolic acids for enzyme inhibition ,activity was estimated, alongside starch digestibility of millet grains was evaluated. Finger millet was found to have high contents of Ca, Mn and Cu minerals. Proso and pearl millet had high protein content, whereas kodo and foxtail millet contained high content of dietary fiber. Phytic acid was comparatively higher in kodo millet, whereas oxalic acid and total tannin content was abundant in finger millet. Total phenolic content and total flavonoid content in bound phenolic fractions were comparatively higher than the free phenolic fractions and total anthocyanin content was found highest in finger millet followed by kodo and pearl millet. The millet varieties showed optimum antioxidant potential studied through different assay methods. Ferulic acid was predominantly found among all the millets in bound fraction of phenolic extract. Furthermore, phenolic acids were used to investigate different docking techniques with α-amylase, α-glucosidase, and leptin receptor enzymes. Docking studies revealed, chlorogenic acid had a high docking score and a high binding affinity against α-amylase, α-glucosidase, and leptin receptor enzymes.

The Use of Different Concentrations of Oxalic Acid to Decrease the Infestation of Varroa Destructor during Autumn Season as One of Integrated Management Methods

Trait results is applying different concentrations of oxalic acid on Varroa mite population parasitoid on honey bee which was conducted in the apiary of the College of Agriculture &amp; Forestry for the year 2020. The concentration treatment of 4.2% showed the lowest mean number of mites falling on the hive board which amounted to 27.42 mites compared with the highest mean of 49.10 mites in the control treatment. This was reflected in the mean number of mites expected inside the cell. It was recorded in the control treatment which amounted to 4910 mites As for the relative effectiveness of the different treatments, the highest mean was recorded in the concentration treatment 3.5% with a mean of 86.84 compared with the lowest mean of 58.85 which was recorded in the concentration treatment 4.2%. As for the treatment efficiency, the highest mean efficiency was recorded 15.91% in the treatment concentration 4.2% compared with the lowest mean of 8.27% which was recorded in the 3.5% concentration treatment. Correlation statistical analysis showed some significant and non-significant differences among some characters in the different treatments.

Precipitation of Ferrous Oxalate from Ferrous Ammonium Sulfate in Oxalic Acid Solution

A kinetic study was conducted experimentally for the precipitation of ferrous oxalate. The ferrous oxalate, in the form of dihydrate (FeC2O4·2H2O), was produced by the acidic dissolution of ferrous ammonium sulfate (Fe(NH4)2(SO4)2) in an aqueous solution of oxalic acid, and then precipitated by nucleation and particle growth from supersaturated solution. The effect of the concentration of ferrous ammonium sulfate and oxalic acid as raw materials was investigated on the kinetics of the ferrous oxalate precipitation. Temperature was kept constant at 25 °C. The surface morphology, atomic compositions, and crystal phase were characterized for the ferrous oxalate precipitate collected. As the initial concentration of ferrous ammonium sulfate increased, the initial precipitation of ferrous oxalate occurred faster. The concentration of oxalic acid did not significantly affect the rate of precipitation of ferrous oxalate. The experimental behavior of ferrous oxalate precipitation was modeled with first-order models of reaction kinetics.

Transcriptome Analysis Revealed the Mechanism of Inhibition of Saprophytic Growth of Sparassis latifolia by Excessive Oxalic Acid.

Sparassis latifolia, a highly valued edible fungus, is a crucial medicinal and food resource owing to its rich active ingredients and pharmacological effects. Excessive oxalic acid secreted on a pine-sawdust-dominated substrate inhibits its mycelial growth, and severely restricts the wider development of its cultivation. However, the mechanism underlying the relationship between oxalic acid and slow mycelial growth remains unclear. The present study reported the transcriptome-based response of S. latifolia induced by different oxalic acid concentrations. In total, 9206 differentially expressed genes were identified through comparisons of three groups; 4587 genes were down-regulated and 5109 were up-regulated. Transcriptome analysis revealed that excessive oxalic acid mainly down-regulates the expression of genes related to carbohydrate utilization pathways, energy metabolism, amino acid metabolism, protein synthesis metabolism, glycan biosynthesis, and signal transduction pathways. Moreover, genes encoding for wood-degrading enzymes were predominantly down-regulated in the mycelia treated with excessive oxalic acid. Taken together, the study results provide a speculative mechanism underlying the inhibition of saprophytic growth by excessive oxalic acid and a foundation for further research on the growth of S. latifolia mycelia.

Oxalic acid degradation in wood-rotting fungi. Searching for a new source of oxalate oxidase

Oxalate oxidase (EC 1.2.3.4) is an oxalate-decomposing enzyme predominantly found in plants but also described in basidiomycete fungi. In this study, we investigated 23 fungi to determine their capability of oxalic acid degradation. After analyzing their secretomes for the products of the oxalic acid-degrading enzyme activity, three groups were distinguished among the fungi studied. The first group comprised nine fungi classified as oxalate oxidase producers, as their secretome pattern revealed an increase in the hydrogen peroxide concentration, no formic acid, and a reduction in the oxalic acid content. The second group of fungi comprised eight fungi described as oxalate decarboxylase producers characterized by an increase in the formic acid level associated with a decrease in the oxalate content in their secretomes. In the secretomes of the third group of six fungi, no increase in formic acid or hydrogen peroxide contents was observed but a decline in the oxalate level was found. The intracellular activity of OXO in the mycelia of Schizophyllum commune, Trametes hirsuta, Gloeophyllum trabeum, Abortiporus biennis, Cerrena unicolor, Ceriosporopsis mediosetigera, Trametes sanguinea, Ceriporiopsis subvermispora, and Laetiporus sulphureus was confirmed by a spectrophotometric assay.

Effects of Lactic Acid Bacteria Fermentation on Physicochemical Properties, Functional Compounds and Antioxidant Activity of Edible Grass

Fermented foods are known worldwide for their functional health properties. In order to promote the relative product development of edible grass, Lactobacillus plantarum (Lp) and Lactobacillus rhamnosus (Lr) were used to ferment edible grass in this study. Effects of fermentation using Lp and Lr in monoculture and binary mixture on physicochemical properties, the contents of functional compounds and the antioxidant activity of edible grass at different fermentation times were investigated by colorimetric method and high-performance liquid chromatography (HPLC). Results show that the pH value and total sugar content of the three fermented edible grasses at the 4th day were lower than those of unfermented water extract (defined as the control sample) and kept almost unchanged at the 7th day. The total polyphenol content and total flavonoid content of the three fermented edible grasses were lower than those of the control sample by the oxidation of phenolic compounds caused by polyphenol oxidases. The highest soluble protein content and superoxide dismutase (SOD) activity were found in the binary mixture of Lp and Lr fermentation at the 7th day, which were respectively 11 and 1.78 times higher than those of control sample. The oxalic acid content of all fermented edible grasses shows a significant decrease with increasing fermentation time, especially for the binary mixture at the 7th day, reaching only 24% of the control sample. However, the contents of lactic acid and succinic acid of the three fermented edible grasses were higher than those of the control sample because of the metabolism of the microorganism. Functional compounds including soluble protein, SOD, lactic acid and succinic acid played the main positive roles in antioxidation, while oxalic acid had a negative correlation with antioxidation. Therefore, the antioxidant activity of edible grass was dramatically enhanced by Lactobacillus strain fermentation.