Malate Research Articles

CHEMICAL CONSTITUENTS, TRADITIONAL USES AND PHARMACOLOGICAL PROPERTIES OF MADHUCA LONGIFOLIA: A REVIEW

Plant extracts and their derivatives are used by almost 80% of the world's population for the treatment of various infections and disorders. The current review was based on the chemical constituents, traditional uses and pharmacological properties of Madhuca longifolia. The Madhuca longifolia (Mahua) Symmachus indica is a huge deciduous tree native to Nepal, India, and Ceylon. It is also known as the Butter nut tree and is a member of the Sapotaceae family. The height of an M. longifolia tree can reach up to 70 feet. The fruiting period of the tree begins between the ages of 8 and 15, and can last up to 60 years. When ripe, the fruits have a greenish yellow colour and are oval in shape [4]. Sugars, vitamin A, ascorbic acid, thiamine, riboflavin, Ca, P, Fe, Mg, Cu, anthocyanins, betains, salts of malic and succinic acid, and many other vitamins and minerals can be found in flowers. It is the rich source of quercetin, 3-O-lrhamnosid, stigmasterol, n-hexacosanol, n-octacosanol, carotene, myricitin, erthrodiol, 3-caproxyolcan-12-en-28-ol, 3-galactoside and Xanthophylls. It was traditionally utilized in bronchitis, diabetes, rheumatism, haemorrhage, ulcer, tonsillitis, pharyngitis, and spongy gums etc. In conclusion, Madhuca longifolia is reported to be effective as antioxidant, analgesic, anti-pyretic, anti-inflammatory, immunosuppression, anti-ulcer, anti-hyperglycaemic, anti-neoplastic and anthelmintic.

Effect of organic acids on fermentation quality and microbiota of horseshoe residue and corn protein powder

This experiment aimed to investigate the impact of malic acid (MA) and citric acid (CA) on the nutritional composition, fermentation quality, rumen degradation rate, and microbial diversity of a mixture of apple pomace and corn protein powder during ensiling. The experiment used apple pomace and corn protein powder as raw materials, with four groups: control group (CON), malic acid treatment group (MA, 10 g/kg), citric acid treatment group (CA, 10 g/kg), and citric acid + malic acid treatment group (MA, 10 g/kg + CA, 10 g/kg). Each group has 3 replicates, with 2 repetitions in parallel, subjected to mixed ensiling for 60 days. The results indicated: (1) Compared to the CON group, the crude protein content significantly increased in the MA, CA, and MA + CA groups (p < 0.05), with the highest content observed in the MA + CA group. The addition of MA and CA effectively reduced the water-soluble carbohydrate (WSC) content (p < 0.05). Simultaneously, the CA group showed a decreasing trend in NDFom and hemicellulose content (p = 0.08; p = 0.09). (2) Compared to the CON group, the pH significantly decreased in the MA, CA, and MA + CA groups (p < 0.01), and the three treatment groups exhibited a significant increase in lactic acid and acetic acid content (p < 0.01). The quantity of lactic acid bacteria increased significantly (p < 0.01), with the MA + CA group showing a more significant increase than the MA and CA groups (p < 0.05). (3) Compared to the CON group, the in situ dry matter disappearance (ISDMD) significantly increased in the MA, CA, and MA + CA groups (p < 0.05). All three treatment groups showed highly significant differences in in situ crude protein disappearance (ISCPD) compared to the CON group (p < 0.01). (4) Good’s Coverage for all experimental groups was greater than 0.99, meeting the conditions for subsequent sequencing. Compared to the CON group, the Shannon index significantly increased in the CA group (p < 0.01), and the Simpson index increased significantly in the MA group (p < 0.05). However, there was no significant difference in the Chao index among the three treatment groups and the CON group (p > 0.05). At the genus level, the abundance of Lentilactobacillus in the MA, CA, and MA + CA groups was significantly higher than in the control group (p < 0.05). PICRUSt prediction results indicated that the metabolic functional microbial groups in the CA and MA treatment groups were significantly higher than in the CON group (p < 0.05), suggesting that the addition of MA or CA could reduce the loss of nutritional components such as protein and carbohydrates in mixed ensilage. In conclusion, the addition of malic acid and citric acid to a mixture of apple pomace and corn protein powder during ensiling reduces nutritional losses, improves fermentation quality and rumen degradation rate, enhances the diversity of the microbial community in ensiled feed, and improves microbial structure. The combined addition of malic acid and citric acid demonstrates a superior effect.

Transcriptional factor MdESE3 controls fruit acidity by activating genes regulating malic acid content in apple.

Acidity is a key factor controlling fruit flavor and quality. In a previous study, combined transcriptome and methylation analyses identified a P3A-type ATPase from apple (Malus domestica), MdMa11, which regulates vacuolar pH when expressed in Nicotiana benthamiana leaves. In this study, the role of MdMa11 in controlling fruit acidity was verified in apple calli, fruits, and plantlets. In addition, we isolated an AP2 domain-containing transcription factor, designated MdESE3, based on yeast one-hybrid (Y1H) screening using the MdMa11 promoter as bait. A subcellular localization assay indicated that MdESE3 localized to the nucleus. Analyses of transgenic apple calli, fruits, and plantlets, as well as tomatoes, demonstrated that MdESE3 enhances fruit acidity and organic acid accumulation. Meanwhile, chromatin immunoprecipitation quantitative PCR (ChIP-qPCR), luciferase (LUC) transactivation assays, and GUS reporter assays indicated that MdESE3 could bind to the ethylene-responsive element (ERE; 5'-TTTAAAAT-3') upstream of the MdMa11 transcription start site, thereby activating its expression. Furthermore, MdtDT, MdDTC2, and MdMDH12 expression increased in apple fruits and plantlets overexpressing MdESE3 and decreased in apple fruits and plantlets where MdESE3 was silenced. The ERE was found in MdtDT and MdMDH12 promoters, but not in the MdDTC2 promoter. The Y1H, LUC transactivation assays, and GUS reporter assays indicated that MdESE3 could bind to the MdtDT and MdMDH12 promoters and activate their expression. Our findings provide valuable functional validation of MdESE3 and its role in the transcriptional regulation of MdMa11, MdtDT, and MdMDH12 and malic acid accumulation in apple.

Standardization on Fermentation of Chia (Salvia hispanica L.)

Aims: To investigate the fermentation parameters physico-chemical characteristics and to conduct sensory evaluation to assess the acceptability of the fermented chia seeds. Study Design: Experimental study involving the fermentation of chia seeds with varying combinations of water, curd, and honey. Assessment of fermentation parameters and physico-chemical characteristics. Microbiological analysis, LAB isolation, and measurement of TSS, acidity, and pH. Sensory evaluation to determine the acceptability of the fermented chia seeds. Place and Duration of Study: The study undertaken during 2020-23 in the Department of Food Science and Nutrition, University of Agricultural Sciences, GKVK, Bangalore, Karnataka. Methodology: Chia seeds subjected to different fermentation treatments involving combinations of water, curd, and honey. Microbiological analysis conducted to assess microbial populations. Isolation of lactic acid bacteria (LAB) to study their presence. Measurement of total soluble solids (TSS), acidity, and pH to evaluate physico-chemical changes during fermentation. Sensory evaluation performed to determine consumer acceptability. Results: Fermentation treatments showed significant differences in soluble solids ranged (1.63 to 8.10), pH (1.87 to 3.87), and acidity, showcasing organic acid content, notably lactic acid (0.04 to 0.23), oxalic acids (0.04 to 0.23), citric acid (0.09 to 0.50), maleic acid (0.06 to 0.35) and succinic acid (0.05 to 0.30. Fermented white chia with distilled water + curd+ honey (FWC3) and Fermented black chia with distilled water + curd+ honey (FBC3) had the statistically higher mean sensory scores.

Silver-loaded poly(vinyl alcohol)/polycaprolactone polymer scaffold as a biocompatible antibacterial system

A chronic nonhealing wound poses a significant risk for infection and subsequent health complications, potentially endangering the patient‘s well-being. Therefore, effective wound dressings must meet several crucial criteria, including: (1) eliminating bacterial pathogen growth within the wound, (2) forming a barrier against airborne microbes, (3) promoting cell proliferation, (4) facilitating tissue repair. In this study, we synthesized 8 ± 3 nm Ag NP with maleic acid and incorporated them into an electrospun polycaprolactone (PCL) matrix with 1.6 and 3.4 µm fiber sizes. The Ag NPs were anchored to the matrix via electrospraying water-soluble poly(vinyl) alcohol (PVA), reducing the average sphere size from 750 to 610 nm in the presence of Ag NPs. Increasing the electrospraying time of Ag NP-treated PVA spheres demonstrated a more pronounced antibacterial effect. The resultant silver-based material exhibited 100% inhibition of gram-negative Escherichia coli and gram-positive Staphylococcus aureus growth within 6 h while showing non-cytotoxic effects on the Vero cell line. We mainly discuss the preparation method aspects of the membrane, its antibacterial properties, and cytotoxicity, suggesting that combining these processes holds promise for various medical applications.

Photoswitchable Catalytic Aerobic Oxidation of Biomass-Based Furfural: A Selective Route for the Synthesis of 5-Hydroxy-2(5H)-furanone and Maleic Acid by Using the CdS/MOF Photocatalyst

Photoswitchable Catalytic Aerobic Oxidation of Biomass-Based Furfural: A Selective Route for the Synthesis of 5-Hydroxy-2(5H)-furanone and Maleic Acid by Using the CdS/MOF Photocatalyst

Valorization of a Local Italian Pear (Pyrus communis L. cv. ‘Petrucina’)

In recent decades, the food production chain has undergone transformations that have profoundly affected the way food is supplied, causing changes in the quality of the final products. Moreover, biodiversity is seriously threatened worldwide, and the valorization of local germplasm is a priority goal for most sectorial policies in Europe and elsewhere. Southern Italy and the Mediterranean basin present a vast heritage of fruit tree cultivars that is gradually being lost. Through this work, we aim to valorize a well-adapted local pear cultivar named Petrucina from the Salento area (southeastern Italy, Apulia region), which has never been studied before in detail. With this aim, the nutritional and nutraceutical features of pear flesh were characterized and compared with a reference pear cultivar that is widespread and well-known in Europe (cv. ‘Conference’). Petrucina fruits have shown a peculiar aromatic compound profile, and a content of up to 398.3, 30.9, and 4.7 mg/100 g FW of malic acid, citric acid, and ascorbic acid, respectively, much higher than that of Conference fruits. Additionally, Petrucina flesh presents a more than triple total phenolic content and an antioxidant activity more than double that of Conference, making Petrucina a true functional food that deserves wide appreciation.

Ternary systems engineered conductive hydrogel with extraordinary strength, environmental adaptability and excellent electrochemical performances for flexible power supply devices

The easy failure, poor environmental adaptability and unsatisfactory electrochemical performances of hydrogels hinder their applications as key components of flexible power supply devices (PSDs). Herein, a PAA-based hydrogel with extraordinary strength and environmental adaptability is designed via a ternary system, consisting of the tannin-modified MXene (TA@MXene), ZnCl2-cellulose and malic acid (MA) electrolyte. The TA@MXene and ZnCl2-cellulose promote the crosslinking of hydrogel via forming multi networks, endowing the hydrogel with 1.9 MPa tensile strength and 620 % stretchability. Furthermore, the hydrogel has 38.4 mS·cm−1 conductivity, thanks to the effective ion transfer channels in the hydrogel. The MA electrolyte provides a stable pH environment via forming an acid ionization system; also, MA and the high-concentration ZnCl2 solution enhance their electrochemical performance at extreme environments. Three typical PSDs were assembled using the resultant hydrogel as electrolyte/electrode. The as-prepared supercapacitors display a high specific capacity (173.5 mAh·g−1), a superior energy density (208.2 Wh·kg−1) and outstanding capacity retention (92.1 % after 5000 cycles); flexible batteries efficiently respond to strain signals, with 0.77 V open-circuit voltage (Voc); the as-assembled TENG has a 110 V Voc (100 % stretching deformation). We present a design strategy for the construction of advanced hydrogels based a ternary system that will promote flexible PSDs towards practical use.

Impact of salt content on Douchi metabolites: biogenic amines, non-volatile compounds and volatile compounds.

The excessive salt intake associated with Douchi has become a topic of controversy. Addressing this concern and enhancing its market competitiveness necessitates the application of salt reduction fermentation in Douchi. Therefore, to promote the application of salt reduction fermentation in Douchi, a comprehensive study was undertaken aiming to investigate the differences in biogenic amines, volatile compounds and non-volatile compounds in Douchi with varying salt content. The findings unequivocally demonstrate that salt hampers the formation of metabolites in Douchi. As the salt content increased, there was a significant decrease (P < 0.05) in the levels of total acid, amino-type nitrogen and free amino acids in Douchi. Notably, when the salt content exceeded 80 g kg-1, there was a substantial reduction (P < 0.05) in putrescine, lactic acid and malic acid levels. Similarly, when the salt content surpassed 40 g kg-1, β-phenethylamine and oxalic acid levels exhibited a significant decline (P < 0.05). Furthermore, the results of E-nose and principal component analysis based on headspace solid phase microextraction gas chromatography-mass spectrometry revealed notable discrepancies in the volatile compound content between Douchi samples with relatively low salt content (40 and 80 g kg-1) and those with relatively high salt content (120, 160 and 200 g kg-1) (P < 0.05). By employing partial least squares discriminant analysis, eight distinct volatile compounds, including o-xylene, benzaldehyde and 1-octen-one, were identified. These compounds exhibited higher concentrations in Douchi samples with relatively low salt content (40 and 80 g kg-1). The sensory results showed that Douchi samples with lower salt content exhibited higher scores in the soy sauce-like and Douchi aroma attributes. In conclusion, this study significantly enhances our understanding of the impact of salt on metabolites in Douchi and provides invaluable insights for the development of salt reduction fermentation in this context. © 2024 Society of Chemical Industry.

Impact of Encapsulated Saccharomyces cerevisiae Yeasts on the Chemical and Sensory Profiles of Sparkling Cider Produced by the Champenoise Method

The cider market has been significantly expanding and gaining momentum in Eastern Europe. As such, the aim of this study was to obtain sparkling cider via the Champenoise method using two Romanian apple varieties (Topaz and Red Topaz) alongside the employment of two fermentations. Four yeast strains were used in the first fermentation, while encapsulated Saccharomyces cerevisiae was used in the second fermentation. The resulting cider was subjected to a comprehensive investigation to quantitatively determine the carbohydrates, organic acids, volatile and phenolic compounds, and amino acids from all the cider samples. A trained panel evaluated the sensory profile of the samples, and a chemometric analysis was used to interpret the data. Secondary fermentation increased the accumulation of malic acid and lactic acid, as well as the volatile profile complexity. The total polyphenol content in the sparkling cider samples increased by almost 20% in the S. cerevisiae sample and over 217% in the P. kluyveri + S. cerevisiae sample compared to the base cider. Additionally, studying the production and consumption trends of sparkling cider offers valuable insights for both producers and consumers. By understanding consumer preferences and refining production techniques, the industry can deliver higher-quality products that better align with market demands.

Impact of the Combination of Chemical and Organic Fertilization on the Growth and Yield of Pineapple under Two Shade Net Conditions

The use of organic sources presents itself as a viable alternative to mitigate the excessive reliance on chemical fertilizers in agricultural practices. However, in the realm of pineapple cultivation, research exploring the synergy between chemical and organic fertilizers remains scarce. In this context, the objective of this research was to evaluate the impact of the combination of chemical and organic fertilizers on the growth and yield of the MD-2 pineapple cultivar under two shade net conditions (installed 45 and 250 days after planting). The experiment was conducted in a split-plot design, with the main plot being the shade net conditions and the sub-plots the five fertilization treatments, which were applied 18 times via drip irrigation (control, 100% chemical fertilization, 50% reduced chemical fertilization, organic fertilization, and a combination of 50% chemical fertilization with organic fertilization). The results showed that the early installation of shade netting 45 days after planting decreases the growth and yield of pineapple; thus, the use of shade netting at this age is not recommended. Regarding fertilization, the combination of 50% chemical fertilization with organic fertilization showed similar growth and yield values compared to 100% conventional chemical fertilization under both shade net conditions. Furthermore, this combination presented similar nitrate and potassium values in the plant and did not negatively affect malic acid content. Therefore, the use of organic fertilizers in pineapple cultivation is a promising strategy to reduce the excessive use of chemical fertilizers, and it could also improve soil fertility.

Strawberry Gel with a Concentration of 83% and 75% as an Extrinsic Stain Remover

Strawberries have many benefits, where the malic acid contained in strawberries acts as a substance that will erode and remove several stains on the surface of teeth, including cleaning extrinsic stains. Gel preparations are widely used in medicines, cosmetics and food products, including toothpaste and teeth whitening agents. The purpose of this study was to determine the effectiveness of strawberry gel with a concentration of 83% and 75% in cleaning teeth with extrinsic stain on academic member of the Health Polytechnic Jakarta I. This study was an Experiment on 30 people who had upper and lower anterior teeth with extrinsic stain as samples. Data collection was done by applying strawberry gel on the surface of the anterior teeth, allowed to stand for 5 minutes, then brushed and rinsed with water. This procedures was done 2 times a day for 5 consecutive days. Changes in extrinsic stain are measured using the Lobene Stain Index which measures the intensity and area of the stain, as well as a combined score of both. The average of combined score with measurements using the Lobene Stain Index for extrinsic stain before being treated with strawberries. Hopefully the score will decreased every day starting from day 1 to day 5 of treatment.

Microwave‐Assisted Preparation of an Acidic Deep Eutectic Solvent: Green Analysis, Characterization and Application

AbstractMicrowave irradiation was postulated to reduce time and energy for deep eutectic solvent (DES) production which is in line with the principle of green chemistry. In this study, the choline chloride (ChCl)‐malic acid (MA) DES was prepared using microwave‐assisted (DES‐Mic) and conventional (DES‐Con) approaches. Microwave was a relatively greener approach as it was rapid (5 min) and consumed 92.8 % energy less than DES‐Con. Moreover, DES‐Mic and DES‐Con exhibited similar physicochemical profiles (pH, solubility, density) and rheological properties. Structural profiling through FTIR analysis suggested hydrogen bond formation between the functional groups of ChCl and MA. The FTIR spectra also did not show structural differences in the DES synthesized using different methods. DES‐Mic and DES‐Con exhibited superior 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (80.8±0.1 and 83.2±0.3 %, respectively) free radical scavenging activities than ChCl (15.6±0.8 %), MA (20.0±1.4 %) and ChCl:MA aqueous mixture without subjected to DES synthesis conditions (ChCl:MAaq; 23.3±0.8 %). Both DES were also proven as more efficient solvents for the extraction of polysaccharides from ramie leaf, as they recorded higher yields (21.4±1.9 and 22.2±1.0 %, respectively) than equimolar of MA (17.7±2.6 %) and ChCl (6.4±0.2 %). Overall, microwave was proven as a more sustainable approach for DES preparation compared to conventional method, which could be further improvised for industrial applications.

Evaluation of a novel depressant PMAA for the separation of fluorite from calcite using NaOl as a collector

It is challenging to separate fluorite from calcite due to their same calcium activated sites on their surfaces. The copolymer of maleic and acylic acid (PMAA) was used to inhibit the calcite in the flotation of fluorite. Micro-flotation results exhibited that sodium oleate (NaOl) had a good ability to collect fluorite and calcite in the scope of pH 7-10. The PMAA treatment prior to NaOl selectively depressed the floatability of calcite while allowed the flotation of fluorite, and the artificial minerals mixture plotted that fluorite/calcite could be effectively separated in the presence of PMAA/NaOl. Zeta potential results suggested that NaOl collector was absorbed on the PMAA-conditioned calcite surface but did not adsorb on the PMAA-conditioned fluorite surface. XPS results and calculational chemistry revealed the chemical interaction occurred between calcite surface and PMAA which was attributed to the calcium ions of calcite surface interacting with -COOH group of PMAA.

SpCTP3 from the hyperaccumulator Sedum plumbizincicola positively regulates cadmium tolerance by interacting with SpMDH1

Cadmium (Cd) is a heavy metal pollutant mainly originating from the discharge of industrial sewage, irrigation with contaminated water, and the use of fertilizers. The phytoremediation of Cd polluted soil depends on the identification of the associated genes in hyperaccumulators. Here, a novel Cd tolerance gene (SpCTP3) was identified in hyperaccumulator Sedum plumbizincicola. The results of Cd2+ binding and thermodynamic analyses, revealed the CXXC motif in SpCTP3 functions is a Cd2+ binding site. A mutated CXXC motif decreased binding to Cd by 59.93%. The subcellular localization analysis suggested that SpCTP3 is primarily a cytoplasmic protein. Additionally, the SpCTP3-overexpressing (OE) plants were more tolerant to Cd and accumulated more Cd than wild-type Sedum alfredii (NHE-WT). The Cd concentrations in the cytoplasm of root and leaf cells were significantly higher (53.75% and 71.87%, respectively) in SpCTP3-OE plants than in NHE-WT. Furthermore, malic acid levels increased and decreased in SpCTP3-OE and SpCTP3-RNAi plants, respectively. Moreover, SpCTP3 interacted with malate dehydrogenase 1 (MDH1). Thus, SpCTP3 helps regulate the subcellular distribution of Cd and increases Cd accumulation when it is overexpressed in plants, ultimately Cd tolerance through its interaction with SpMDH1. This study provides new insights relevant to improving the Cd uptake by Sedum plumbizincicola.

A comprehensive evaluation of different responses of supplementary light qualities on physiological and biochemical mechanisms of ‘Kyoho’ grape

Grape is an economically important fruit crop worldwide, for which light qualities play a diverse role in vineyard growth and development. However, the regulatory mechanisms between different light qualities and the quality of plant growth at the morphophysiological and pomological levels remain unknown. Therefore, in the current study, we studied plant physiological, biochemical and genetical analysis to investigate the response of all seven light qualities, including red (R), blue (B), white (W), 1-red, 1 blue (1R1B), 2-red, 1-blue (2R1B), 1-red, 2-blue (1R2B), and natural (N, was used as control group) to evaluate ‘Kyoho'grape (Vitis labrusca L. × V. vinifera) morphophysiological, pomological traits at light responsive transcriptional pathway, which revealed the possible networking metabolism controlling fruit quality and quantity of grape plant. Our results showed that photosynthetic indicators such as leaf stomata, number of stomata, and longitudinal and transverse diameter of stomata improved under red and blue light qualities as compared to white light. Leaf gas exchange indicators showed that net photosynthetic rate, transpiration rate, intercellular CO2 concentration rate, total conductance to CO2, stomatal conductance, conductance to water vapor, maximal quantum yield of PS (II), actual photochemical quantum efficiency, electron transfer chain, and non-photochemical quantum efficiency improve under blue and red light. Photosynthetic pigments showed that chlorophyll a and b, carotenoid, and total pigment contents improved under blue and red light. Nutrient elements showed that potassium, phosphorous, magnesium, calcium, iron, and zinc contents improved under blue and red light. Morphological and organic acid indicators such as the appearance of fruit shape, firmness, and titratable acidity improved under blue and light. However, there was a notable increment in the total soluble sugar under blue and red light as compared to natural light. The composition of sugar including (sucrose, fructose, glucose) and organic acids (tartaric acid, citric acid, and malic acid) improved under blue and red light (fruits) and showed notable reductions for tartaric acid under blue and red light (leaves) as compared to natural light. Aromatic compounds showed that esters, aldehydes, acetaldehyde, 2-hexenal, ethyl acetate, n-propyl acetate, butanoic acid, ethyl ester, 1-hexanol, 2-ethyl, 2-propanone, and 1‑hydroxyl, improved under blue and red light. Further, changes in enhanced expression of light-responsive genes including VvCRYI, VvCRY2, VvPHYA, VvPHYB, VvCOP1, VvHY5, VvHYH, and VvPIF4 upregulated under blue and red light, while VvPIF3.1 down-regulated as compared to natural light. Also, chlorophyll synthesis-related genes including VvSGR, VvPAO, and VvCHLH upregulated under blue and red light, while VvNYC1, VvPPH, and VvPOR showed noticeable changes under blue and red light as compared to natural light. Interestingly, most of the relative genes were highly expressed in fruits as compared to leaves. Finally, we have established correlation and principal component analysis for indicators in grapes. Current findings provide novel mechanisms by which different responses of supplementary light control the plant fruit quality of grapes.

Mechanism for Fe(III) to decrease cadmium uptake of wheat plant: Rhizosphere passivation, competitive absorption and physiological regulation

The presence of dissolved Fe(III) and Fe(III)-containing minerals has been found to alleviate cadmium (Cd) accumulation in wheat plants grown in Cd-contaminated soils, but the specific mechanism remains elusive. In this work, hydroponic experiments were conducted to dissect the mechanism for dissolved Fe(III) (0–2000 μmol L−1) to decrease Cd uptake of wheat plants and study the influence of Fe(III) concentration and Cd(II) pollution level (0–20 μmol L−1) on the Cd uptake process. The results indicated that dissolved Fe(III) significantly decreased Cd uptake through rhizosphere passivation, competitive absorption, and physiological regulation. The formation of poorly crystalline Fe(III) oxides facilitated the adsorption and immobilization of Cd(II) on the rhizoplane (over 80.4 %). In wheat rhizosphere, the content of CaCl2-extractable Cd decreased by 52.7 % when Fe(III) concentration was controlled at 2000 μmol L−1, and the presence of Fe(III) may reduce the formation of Cd(II)-organic acid complexes (including malic acid and succinic acid secreted by wheat roots), which could be attributed to competitive reactions. Down-regulation of Cd uptake genes (TaNramp5-a and TaNramp5-b) and transport genes (TaHMA3-a, TaHMA3-b and TaHMA2), along with up-regulation of the Cd efflux gene TaPDR8-4A7A, contributed much to the reduction of Cd accumulation in wheat plants in the presence of Fe(III). The inhibitory effect of Fe(III) on Cd uptake and transport in wheat plants declined with increasing Cd(II) concentration, particularly at 20 μmol L−1. This work provides important implications for remediating Cd-contaminated farmland soil and ensuring the safe production of wheat by using dissolved Fe(III) and Fe(III)-containing minerals.

The synergistic effect of typical chiral organic acids and solution chemistry conditions on the transport of 2-arylpropionic acid chiral derivatives in porous media

The hazards of man-made chiral compounds are of great public concern, with reports of worrying stereoselective compounds and an urgent need to assess their transport. This study evaluated the transport of 2-arylpropionic acid derivatives enantiomers (2-APA) in porous media under a variety of solution chemistry conditions via column packing assays. The results revealed the introduction of Malic acid (MA) enantiomers enhanced the mobility of 2-APA enantiomers, but the enhancement effect was different for different 2-APA enantiomers. Batch sorption experiments confirmed that the MA enantiomers occupied the sorption site of the quartz sand, thus reducing the deposition of the 2-APA enantiomer. Homo- or heterochirality between 2-APA and MA dominates the transport of 2-APA enantiomers, with homochirality between them triggering stronger retention and vice versa. Further evaluating the effect of solution chemistry conditions on the transport of 2-APA enantiomers, increased ionic strength attenuated the mobility of 2-APA enantiomers, whereas introduced coexisting cations enhanced the retention of 2-APA enantiomers in the column. The redundancy analyses corroborated these solution chemistry conditions were negatively correlated with the transport of 2-APA enantiomers. The coupling of pH and these conditions reveals electrostatic forces dominate the transport behavior and stereoselective interactions of 2-APA enantiomers. Distinguishing the transport of enantiomeric pair helps to understand the difference in stereoselectivity of enantiomers and promises to remove the more hazardous one.

Maleic acid crosslinked starch/polyvinyl alcohol blend films with improved barrier properties for packaging applications

Incorporating starch, which is a potential biodegradable substitute for petroleum-based polymers, into conventional polymers is challenging owing to limitations in processability and weak-performing resulting materials. Herein, corn starch/polyvinyl alcohol (PVA) blend films (starch: PVA ratio of 50:50) were prepared via the solvent casting method using glycerol as a plasticizer and with varying concentrations of maleic acid as the crosslinking agent. Fourier transform infrared spectroscopy revealed the molecular interactions of the maleic acid crosslinker with the polymeric network of starch and PVA through an ester linkage. The properties of the films were strongly dependent on the maleic acid concentration. An increasing maleic acid concentration imparted hydrophobicity to the film; therefore, water swelling was significantly reduced, and water resistance was enhanced. The film containing 20 wt% maleic acid exhibited excellent barrier properties, with the lowest oxygen and water vapor transmission rates of 0.5 ± 0.2 cc/m2⋅day and 232.3 ± 5.4 g/m2⋅day, respectively. Moreover, the mechanical properties of the film improved with increasing crosslinking. This study demonstrates that the addition of maleic acid leads to an improvement in the overall performance of starch/PVA blend films. Therefore, maleic acid-crosslinked films can be used as barrier materials in food packaging applications.

Metabolic engineering of Aspergillus niger for accelerated malic acid biosynthesis by improving NADPH availability.

Microbial production of L-malic acid from renewable carbon sources has attracted extensive attention. The reduced cofactor NADPH plays a key role in biotransformation because it participates in both biosynthetic reactions and cellular stress responses. In this study, NADPH or its precursors nicotinamide and nicotinic acid were added to the fermentation medium of Aspergillus niger RG0095, which significantly increased the yield of malic acid by 11%. To further improve the titer and productivity of L-malic acid, we increased the cytoplasmic NADPH levels of A. niger by upregulating the NAD kinases Utr1p and Yef1p. Biochemical analyses demonstrated that overexpression of Utr1p and Yef1p reduced oxidative stress, while also providing more NADPH to catalyze the conversion of glucose into malic acid. Notably, the strain overexpressing Utr1p reached a malate titer of 110.72±1.91gL-1 after 108h, corresponding to a productivity of 1.03±0.02gL-1h-1. Thus, the titer and productivity of malate were increased by 24.5% and 44.7%, respectively. The strategies developed in this study may also be useful for the metabolic engineering of fungi to produce other industrially relevant bulk chemicals.