Durable CO2 conversion in the proton-exchange membrane system.

Electrolysis that reduces carbon dioxide (CO2) to useful chemicals can, in principle, contribute to a more sustainable and carbon-neutral future1-6. However, it remains challenging to develop this into a robust process because efficient conversion typically requires alkaline conditions in which CO2 precipitates as carbonate, and this limits carbon utilization and the stability of the system7-12. Strategies such as physical washing, pulsed operation and the use of dipolar membranes can partially alleviate these problems but do not fully resolve them11,13-15. CO2 electrolysis in acid electrolyte, where carbonate does not form, has therefore been explored as an ultimately more workable solution16-18. Herein we develop a proton-exchange membrane system that reduces CO2 to formic acid at a catalyst that is derived from waste lead-acid batteries and in which a lattice carbon activation mechanism contributes. When coupling CO2 reduction with hydrogen oxidation, formic acid is produced with over 93% Faradaic efficiency. The system is compatible with start-up/shut-down processes, achieves nearly 91% single-pass conversion efficiency for CO2 at a current density of 600 mA cm-2 and cell voltage of 2.2 V and is shown to operate continuously for more than 5,200 h. We expect that this exceptional performance, enabled by the use of a robust and efficient catalyst, stable three-phase interface and durable membrane, will help advance the development of carbon-neutral technologies.

Reaction Environment Regulation for Electrocatalytic CO2 Reduction in Acids.

The electrocatalytic CO2 reduction reaction (CO2RR) is a sustainable route for converting CO2 into value-added fuels and feedstocks, advancing a carbon-neutral economy. The electrolyte critically influences CO2 utilization, reaction rate and product selectivity. While typically conducted in neutral/alkaline aqueous electrolytes, the CO2RR faces challenges due to (bi)carbonate formation and its crossover to the anolyte, reducing efficiency and stability. Acidic media offer promise by suppressing these processes, but the low Faradaic efficiency, especially for multicarbon (C2+) products, and poor electrocatalyst stability persist. The effective regulation of the reaction environment at the cathode is essential to favor the CO2RR over the competitive hydrogen evolution reaction (HER) and improve long-term stability. This review examines progress in the acidic CO2RR, focusing on reaction environment regulation strategies such as electrocatalyst design, electrode modification and electrolyte engineering to promote the CO2RR. Insights into the reaction mechanisms via in situ/operando techniques and theoretical calculations are discussed, along with critical challenges and future directions in acidic CO2RR technology, offering guidance for developing practical systems for the carbon-neutral community.

Low-coordination Nanocrystalline Copper-based Catalysts through Theory-guided Electrochemical Restructuring for Selective CO2 Reduction to Ethylene.

Revealing the dynamic reconstruction process and tailoring advanced copper (Cu) catalysts is of paramount significance for promoting the conversion of CO2 into ethylene (C2H4), paving the way for carbon neutralization and facilitating renewable energy storage. In this study, we initially employed density functional theory (DFT) and molecular dynamics (MD) simulations to elucidate the restructuring behavior of a catalyst under electrochemical conditions and delineated its restructuring patterns. Leveraging insights into this restructuring behavior, we devised an efficient, low-coordination copper-based catalyst. The resulting synthesized catalyst demonstrated an impressive Faradaic efficiency (FE) exceeding 70 % for ethylene generation at a current density of 800 mA cm-2. Furthermore, it showed robust stability, maintaining consistent performance for 230 hours at a cell voltage of 3.5 V in a full-cell system. Our research not only deepens the understanding of the active sites involved in designing efficient carbon dioxide reduction reaction (CO2RR) catalysts but also advances CO2 electrolysis technologies for industrial application.

Effects of soil factors on dimethyl disulfide desorption and the risk of phytotoxicity to newly-planted seedlings.

Dimethyl disulfide (DMDS) is a relatively new soil fumigant used in agro-industrial crop production to control soil-borne pests that damage crops and reduce yield. The emissions of DMDS after fumigation reduce soil concentrations thus reducing the risk of phytotoxicity to newly planted crops. However, the factors affecting the desorption of DMDS from soil are unclear. In our study, the desorption characteristics of DMDS from soil were measured in response to continuous ventilation. The degradation of DMDS in soil was examined by thermal incubation. The phytotoxic response of newly-planted cucumber (Cucumis sativus) seedlings to DMDS residues was measured by a sand culture experiment. The results showed DMDS desorption and degradation rates fit a first-order model; that 92% of the DMDS desorption occurred in the first hour after fumigant application; and that residue concentrations in the soil at the end of the ventilation period were unlikely to be phytotoxic to newly-planted cucumber seedlings. By the third day of ventilation, the average desorption rate (ADR) of DMDS in Wenshan soil was 4.0 and 3.6 times, respectively, faster than that in Shunyi and Suihua soils and the ADR of DMDS in soil decreased by 40.0% when the soil moisture content increased from 3% to 12% (wt/wt). Moreover, within one hour of ventilation, the ADR of DMDS in soil decreased by 20.1% when the soil bulk density increased from 1.1 to 1.3 g cm-3. The degradation of DMDS in soil, however, was mostly influenced by soil type and moisture content. A slow degradation rate resulted in a high initial desorption concentration of DMDS in soil. Our results indicated that DMDS desorption from soil in response to continuous ventilation was affected by the soil type, moisture content and bulk density. Rapid degradation of DMDS in soil will lower the risk of phytotoxic residues remaining in the soil and reduce emissions during the waiting period. Acceleration of emissions early in the waiting period by managing soil moisture content or increasing soil porosity may shorten the duration of emissions. Alternatively, soil extraction technology could be developed to recover and reduce fumigant emissions.

Advanced Platinum-Based Oxygen Reduction Electrocatalysts for Fuel Cells.

ConspectusFuel cells are among the cutting-edge energy technologies. Their commercial development is still hindered by noble platinum (Pt) catalysts for the oxygen reduction reaction (ORR) at the cathode, which not only determine the energy conversion efficiency and service life but also are closely related to the cost and broad application of fuel cells. Given the bright and enormous future of fuel cells, ORR catalysts should possess highly efficient performance yet meet the acceptable Pt costs for large-scale application. Extensive efforts are concentrated on the optimization of Pt-based nanostructures and upgradation of functional carriers to achieve the low-cost and high-activity Pt-based catalysts. By improving the Pt utilization and accessible surface, reducing Pt consumption and catalyst costs, accelerating mass exchange and electron transfer, alleviating the corrosion and agglomeration of carriers and Pt, accompanying with the assistance of robust yet effective functional supports, the service level and life of Pt-based electrocatalysts would be significantly improved and fuel cells could get into commercial market covering broader applications.In this Account, we focus on the recent development of Pt-based catalysts to figure out the problems associated with ORR catalysts in fuel cells. Recent development of Pt-based catalysts is discussed in different stages: (1) multiscale development of Pt-based nanostructures; (2) multielement regulation over Pt-based alloy composition; (3) upgradation of carbon and noncarbon support architectures; (4) development of integrated Pt-based catalysts for fuel cells. Finally, we propose some future issues (such as reaction mechanism, dynamic evolutions, and structure-activity relationship) for Pt-based catalysts, which mainly involve the preparation strategy of Pt-integrated catalysts (combination of Pt nanostructures with nanocarbons), performance evaluation (standard measurement protocols, laboratory-level rotating disk electrode (RDE) measurements, application-level membrane electrode assembly (MEA) service test), advanced interpretation techniques (spectroscopy, electron microscopy, and in situ monitoring), and cutting-edge simulation/calculations and artificial intelligence (simulation, calculations, machine learning, big data screening). This Account calls for the comprehensive development of multiscale, multicomponent, and high-entropy Pt-based alloy nanostructures, and novel and stable carriers, which provide more available options for rational design of low-cost and high-performance Pt-integrated ORR catalysts. More importantly, it will give an in-depth understanding of the reaction mechanism, dynamic development, and structure-performance relationship for Pt-based catalysts in fuel cells and related energy technologies.

First report in China of Fusarium humuli as a causative agent of Chinese yam wilt.

Wilt is one the most serious soil-born fungal diseases of Chinese yam (Dioscorea polystachya Turczaninow cv. Tiegun), affecting plant production in many growing regions in Jiangxi province, China. The average annual incidence of wilt is 45-80%. In 2020, affected plants with wilt symptoms including withered and dried leaves, vascular discoloration, and brown necrotic stem lesions at the soil line or in the crown of the plant (Figure 1A-D) were collected from the Ruichang, Yongfeng and Taihe production areas (four fields per location) in Jiangxi province. A total of fifteen isolates were recovered from the infected stem tissues of Chinese yam and purified by single spore cultures on PDA growth medium. The fifteen isolates were similar in morphology so isolate JXRC11 was selected to be representative of the group. Pure fungal colonies of JXRC11were found to be round, white, with margin entire (Figure 1E). Macroconidia with 3-5 septations were straight to slightly curved, 23.8-40.3 µm in length and 2.6-3.9 µm in width, with predominantly 5-septate macroconidia on carnation leaf agar (CLA) (Figure 1F). However, neither microconidia or chlamydospores were observed on CLA. The morphological characteristics of the isolate were consistent with the description observed previously for Fusarium humuli species complex (Wang et al. 2019). To confirm morphological identification, ITS, CAM, TEF-1α, RPB1 and RPB2 were amplified using the primers ITS5/ITS4 (White et al. 1990), CL1/CL2A (O'Donnell et al. 2000), EF1/EF2 (O'Donnell et al. 1998), Fa/G2R (O'Donnell et al. 2010), and 5f2/11ar (O'Donnell et al. 2010), respectively. BLASTn analysis of the ITS sequence (GenBank accession no. MZ768912), EF-1α (MZ824669), CAM (MZ824670), RPB1 (MZ824672) and RPB2 (MZ824673) alignment showed 99.55%, 99.68%, 99.85%, 97.61% and 99.76% identity to those of F. humuli CQ1039 (MK280845, MK289570, MK289712, MK289840 and MK289724), respectively. Multilocus phylogenetic analyses showed that the sequences of ITS, CAM, EF-1α, RPB1, and RPB2 of the isolate belonged to the incarnatum clade (FIESC-33) of the F. incarnatum-equiseti species complex with an independent branch (Figure 2). Pathogenicity tests were conducted on one-month-old Chinese yam seedlings using a seedling root dip method (Li et al. 2013). The roots and rhizomes of seedlings grown to two meters in height were dipped into spore suspensions (1×106 spores/mL) of isolate JXRC11 for 30 min and then transferred into 20 cm diameter plastic pots containing steam-sterilized soil and placed in a greenhouse under 12 h photoperiod. After 15 d, the inoculated seedlings showed typical wilt symptoms similar to those observed in farm fields, whereas the control remained unaffected (Figure 1G-H). The pathogen was then re-isolated from the infected plants, the re-isolations were identified as F. humuli by sequencing EF-1α, fulfilling the Koch's postulates. It has been reported that the pathogen F. oxysporum Schlecht causes Fusarium wilt in five species of Dioscorea (Nwankiti and Arene, 1978). Moreover, at least 5 species of Fusarium were identified as a causative agent of Chinese yam wilt (Fang et al. 2020). To our knowledge, this is the first report of Fusarium wilt disease on Chinese yam caused by a member of the F. humuli in Jiangxi, China. This report will contribute to developing management strategies to control the disease.

Organic fertilizers activate soil enzyme activities and promote the recovery of soil beneficial microorganisms after dazomet fumigation.

Soil fumigation can reduce the impact of soil-borne diseases, weeds and insect pests on commercial crop production. Unfortunately, fumigation also kills beneficial microorganisms. In this study, we explored if dazomet fumigation could be used in combination with organic fertilizers (silicon fertilizer, potassium humate organic fertilizer, Bacillus microbial fertilizer, and mixtures of the last two) to reduce its impact on soil beneficial microorganisms. We evaluated the effects of adding these fertilizers after fumigation on the soil's physical and chemical properties and its enzyme activities, as well as its effects on the soil microbial communities under continuous production for >20 years. We found that fertilizers applied after fumigation increased the soil nitrate nitrogen content by 11.6%-29.4%, increased available potassium content by 5.6%-26.3% and increased organic matter content by 28.5%-48.8%. In addition, soil conductivity and water content increased significantly by 8.2%-26.5% and 8.0%-16.0%, respectively. The activities of soil catalase and soil sucrase were significantly increased by 6.2%-15.9% and 133.1%-238.5%, respectively. High-throughput DNA sequencing showed that fertilizers applied after fumigation increased the relative abundance of the phyla Proteobacteria, Actinobacteria and Ascomycota; and the genera Sphingomonas, Chaetomium and Mortierella. Silicon fertilizer applied after fumigation has the most significant promotion effect on soil micro-ecological health. The results showed that organic fertilizers applied after fumigation can improve the soil's fertility, activate soil enzyme activities and promote the recovery of soil beneficial microorganisms, which are all factors that improve crop quality and yield.

Molecular Methods for Identification and Quantification of Foodborne Pathogens.

Foodborne pathogens that enter the human food chain are a significant threat worldwide to human health. Timely and cost-effective detection of them became challenging for many countries that want to improve their detection and control of foodborne illness. We summarize simple, rapid, specific, and highly effective molecular technology that is used to detect and identify foodborne pathogens, including polymerase chain reaction, isothermal amplification, loop-mediated isothermal amplification, nucleic acid sequence-based amplification, as well as gene chip and gene probe technology. The principles of their operation, the research supporting their application, and the advantages and disadvantages of each technology are summarized.

Effects of chloropicrin fumigation combined with biochar on soil bacterial and fungal communities and Fusarium oxysporum.

Chloropicrin (CP) can cause long-term damage to beneficial microbes which reduces soil health. Biochar (BC) can mitigate against the effects of CP by reducing the time for beneficial microbes to recover after CP fumigation. In this study, we used Real-Time Quantitative PCR to determine the effects of different rates of BC added to CP-fumigated soil on the speed of recovery of bacteria and fungi population and on changes to gene copy number of the target pathogen Fusarium oxysporum. And then we compared the structure and composition of the beneficial microbial community in the different treatments soil by using High throughput Illumina sequencing. As the results shown, adding 1 or 3% BC after CP fumigation accelerated the recovery of bacterial and fungal populations without increasing F. oxysporum abundance. BC also promoted the recovery of beneficial bacteria Rokubacteria and Latescibacteria damaged by CP. And these two bacteria may be related to the immunity of soil to F. oxysporum. In CP-fumigated soil, BC improved the disease resistance of the soil by increasing beneficial microbes, such as Steroidobacter, Sphingomonas, Purpureocillium and Mortierella. This combination of CP and BC is a new concept that could encourages the development of a healthy and sustainable soil ecosystems while controlling plant pathogens.

Chloropicrin alternated with dazomet improved the soil's physicochemical properties, changed microbial communities and increased strawberry yield.

Chloropicrin (Pic) and dazomet (DZ) are effective soil fumigants that are often used to reduce soil-borne pathogens that would otherwise reduce crop yield. As Pic is scheduled to be banned, we investigated whether its consumption could be halved by alternating it with DZ. We observed that Pic alternated with DZ increased the soil NH4+-N content by 28.74-47.07 times, increased available potassium content by 40.80%-46.81% and increased electrical conductivity by 39.23%-85.81%. It generally improved the soil's physicochemical properties. High-throughput DNA sequencing showed that Pic alternated with DZ changed the taxonomic diversity of bacteria and fungi by increasing the relative abundance of Bacillus and Firmicutes, and by decreasing Proteobacteria, Acidobacteria and Sphingomonas. Moreover, Pic alternated with DZ can inhibit key soil pathogens by more than 90% and significantly increased strawberry yield by 78.22%-116.12%. In terms of strawberry production, we recommend using DZ in the first year and Pic in the second year. Our results showed significant ecological benefit and yield benefit when Pic consumption was halved by alternating it with DZ.

Comparison of headspace solid-phase microextraction and solvent extraction method for the simultaneous analysis of various soil fumigants in soil or water by gas chromatography-mass spectrometry.

The quantity of soil fumigants has increased globally that has focused attention on their environmental behavior. However, simultaneous analysis of traces of fumigant residues is often unreported because analysis methods are not readily available to measure them at low concentrations. In this study, typical solvent extraction methods were compared with headspace solid-phase microextraction methods. Both methods can be used for simultaneously measuring the concentrations of five commonly used soil fumigants in soil or water. The solvent extraction method showed acceptable recovery (76-103%) and intraday relative standard deviations (0.8-11%) for the five soil fumigants. The headspace solid-phase microextraction method also showed acceptable recovery (72-104%) and precision rates (1.3-17%) for the five soil fumigants. The solvent extraction method was more precise and more suitable for analyzing relatively high fumigant residue levels (0.05-5 µg/g) contained in multiple soil samples. The headspace solid-phase microextraction method, however, had a much lower limits of detection (0.09-2.52 µg/kg or µg/L) than the solvent extraction method (5.8-29.2 µg/kg), making headspace solid-phase microextraction most suitable for trace analysis of these fumigants. The results confirmed that the headspace solid-phase microextraction method was more convenient and sensitive for the determination of fumigants to real soil samples.

Comparative analysis of the effects of five soil fumigants on the abundance of denitrifying microbes and changes in bacterial community composition.

Soil fumigation is currently the most effective method for controlling soil-borne pests and diseases in high-value crops. To better understand the effect of chloropicrin (CP), dazomet (DZ), dimethyl disulfide (DMDS), allyl isothiocyanate (AITC) and 1,3-dichloropropene (1,3-D) fumigants on soil microorganisms, this study monitored changes in the diversity and community composition of soil bacteria involved in denitrification using real-time PCR and high-throughput gene sequencing techniques. These five fumigants significantly decreased the bacterial population size in some phyla including Proteobacteria, Chloroflexi and Acidobacteria, and increased the bacterial population size in other phyla such as Firmicutes, Gemmatimonadetes, Actinobacteria, Verrucomicrobia, Saccharibacteria and Parcubacteria. Although bacterial diversity declined after CP fumigation, it was briefly stimulated by the other four fumigants. Meanwhile, all five fumigants temporarily decreased populations of denitrifying bacteria containing the napA, narG, nirS or nirK enzyme-encoding genes. Denitrifiers bearing the cnorB, qnorB or nosZ genes were relatively stable following DZ and DMDS fumigation. However, cnorB and nosZ decreased initially following CP, AITC and 1,3-D fumigation. Simultaneously, the abundance of qnorB significantly increased in AITC and 1,3-D fumigated soils. These results showed that soil fumigation significantly shifted the abundance and community structure of denitrifying bacteria. This study will help to predict the response of different phyla of denitrifying bacteria to soil fumigation.

Evaluation of the influence of temperature and relative humidity on the permeability of four films to the fumigant dimethyl disulfide.

Dimethyl disulfide (DMDS) is an alternative fumigant to methyl bromide that was phased out globally due to its stratospheric ozone-depleting properties. Covering the surface of the soil with a plastic tarpaulin or 'barrier film' when using a soil fumigant is typically used to retain fumigants in the soil and to reduce emissions. Emission levels depend on the film's permeability, which varies mainly according to the film's material, the type of fumigant and the environmental conditions. We used specialized laboratory equipment to test the permeability of four films to DMDS under similar temperature and relative humidity (RH) conditions present in the field: polyethylene (PE), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) and ethylene vinyl alcohol copolymer (EVOH). This report presents evidence that the influence of temperature and relative humidity on the permeability of four films to the fumigant DMDS: PE，PVC,PVDC, EVOH. This research confirmed that PE and PVC films are relatively permeable to DMDS and PVC was more unstable to a range of environmental condition than other three films; PVDC and EVOH films are relatively impermeable to the fumigant DMDS and the permeability of PVDC was more stable to a range of environmental conditions than EVOH. The cumulative emissions of DMDS from soil covered with PE, PVC, PVDC or EVOH were 21.38%, 27.51%, 1.59% and 1.52%, respectively. As the permeability of PVDC was more stable to a range of environmental conditions than EVOH, PVDC shows potential for use in the field with a volatile fumigant such as DMDS.

Effect of films on dimethyl disulfide emissions, vertical distribution in soil and residues remaining after fumigation.

An improved understanding of the conditions that influence dimethyl disulfide (DMDS) emissions, distribution through the soil and residues remaining after treatment will help to optimise the use of this relatively new soil fumigant for the control of soil-borne pests and disease, and to improve the safety of DMDS use. Using soil columns in the laboratory, the cumulative emission of DMDS using doses of 40 and 80 g m-2 were, respectively, 74.8% and 68.9% with bare soil, 4.2% and 9.6% with polyethylene (PE) film, 0.02% and 0.2% with Totally Impermeable Film (TIF). Six hours after injection DMDS was detected mostly 5 cm below the surface and very little at 25 cm when used on bare soil, compared with much higher and similar concentrations of DMDS 5 and 25 cm deep when films were used. DMDS at the injection port exceeded 1 µg cm-3 for longer when a film was used instead of bare soil. The total DMDS soil residues remaining in the soil, as a percentage of the initial DMDS dose at 40 or 80 g m-2 were, respectively, 1.17 and 5.58 with TIF, 0.91 and 1.18 with PE, 0.47 and 0.47 with bare soil. DMDS rose rapidly upwards and escaped from bare soil, whereas PE or TIF significantly reduced DMDS emissions, retained elevated DMDS concentrations in the soil for longer and distributed them more uniformly in the soil. TIF performed better in these respects than PE. TIF also reduced the potential environmental impact of DMDS more than PE, especially at the higher dose.

Environmental Factors and Soil Amendment Affect the Decomposition Rate of Dazomet Fumigant.

Dazomet (3,5-dimethyl-1,3,5-thiadiazinane-2-thione) is widely used as a soil fumigant for controlling soil-borne diseases and pests in China and other agricultural countries. The active ingredient of dazomet is its degradation product, methyl isothiocyanate. Little is known about the environmental conditions that affect the degradation of dazomet in soil. In this study, we conducted laboratory incubation experiments to test the effects of several environmental factors, including soil texture, water content, temperature, pH, and soil amendments, such as chicken manure or urea fertilizer, on the decomposition of dazomet. Results showed that dazomet degradation in soil is an abiotic process strongly dependent on soil texture, water content, temperature, and pH. Decomposition rates differed greatly in various soils, depending mainly on soil physicochemical properties such as pH and organic matter content. The degradation rate increased by 15 to 24 times and by 16 to 37 times when soil temperature increased from 5 to 45°C, and water content increased from 10 to 30%, respectively. Dazomet degraded faster in alkaline versus acidic soil. Both chicken manure and urea fertilizer moderately slowed dazomet degradation. Dazomet was degraded in soil mainly by hydrolysis. The results of our study contribute to a better understanding of the environmental behavior of dazomet, potentially leading to its more efficient, safe, profitable, and effective use by farmers.

Effects of oil extracts of Eupatorium adenophorum on Phytophthora capsici and other plant pathogenic fungi in vitro.

The antifungal activity of oils extracted from Eupatorium adenophorum was tested against five phytopathogens in vitro. Oil extracts inhibited the mycelial growth of Phytophthora capsici which causes phytophthora blight in pepper. The minimum inhibitory concentration of oils against P. capsici was 500µg/ml after 7days incubation. At the ultrastructural level, oil extracts caused complete disorganization of intracellular organelles, cytoplasm depletion, disruption of cytoplasmic membranes and the cell wall. Membrane permeability increased with the increasing concentration of oil extracts. These results suggested that these oil extracts exhibited multiple modes of action including disruption of the cell membrane system. Furthermore, oil extracts combined with synthetic fungicides synergistically inhibited mycelial growth of P. capsici, which creates the possibility of reducing fungicide concentration needed to successfully control phytophthora blight in commercial pepper production. This study's use of multiple methods of analysis has increased our understanding of the mode of action of E. adenophorum oil extracts against P. capsici.

Systematic assessment of the antifungal mechanism of soil fumigant methyl isothiocyanate against Fusarium oxysporum.

Fusarium oxysporum is an important phytopathogenic fungus, it can be controlled by the soil fumigant methyl isothiocyanate (MITC). However, the antimicrobial mechanism of MITC against F. oxysporum, especially at the transcriptional level, is still unclear. In this experiment, the antimicrobial mechanism of MITC against F. oxysporum was investigated. Our results indicated that when F. oxysporum was exposed to 6 mg/L MITC for 12 h, the inhibitory rate of MITC on F. oxysporum was 80%. Transmission electron microscopes showed that the cell wall and membrane of F. oxysporum had shrunk and folded, vacuoles increased, and mitochondria swelled and deformed. In addition, the enzyme activity of F. oxysporum treated with MITC showed a decrease of 32.50%, 8.28% and 74.04% in catalase, peroxidase and superoxide dismutase, respectively. Transcriptome sequencing of F. oxysporum was performed and the results showed that 1478 differentially expressed genes (DEGs) were produced in response to MITC exposure. GO and KEGG analysis showed that the DEGs identified were involved in substance and energy metabolism, signal transduction, transport and catalysis. MITC disrupted cell homeostasis by influencing the expression of some key genes involved in chitin synthase and detoxification enzymes production, but F. oxysporum also protected itself by up-regulating genes involved in energy synthesis (such as upregulating acnA, CS and LSC2 in TCA). qRT-PCR data validated the reliability of transcriptome data. Our research used biochemical and genetic techniques to identify molecular lesions in the mycelia of F. oxysporum exposed to MITC, and provide valuable insights into the toxic mechanism of pathogenic fungi mediated by MITC. These techniques are also likely to be useful for rapidly screening and identifying new, environmentally-friendly soil fumigants that are efficacious against fungal pathogens.

The potential for reducing aflatoxin B1 contamination of stored peanuts by soil disinfection.

Aflatoxins from the fungus Aspergillus flavus (A. flavus) that contaminate stored peanuts is a major hazard to human health worldwide. Reducing A. flavus in soil can decrease the risk of aflatoxins in stored peanuts. In this experiment, we determined whether peanuts grown on soil fumigated with dazomet (DZ), metham sodium (MS), allyl isothiocyanate (AITC), chloropicrin (PIC) or dimethyl disulfide (DMDS) would reduce of the quantity of A. flavus and its toxin's presence. The results of bioassays and field tests showed that PIC was the most effective fumigant for preventing and controlling A. flavus, followed by MS. PIC and MS applied to the soil for 14 d resulted in LD50 values against A. flavus of 3.558 and 4.893 mg kg-1, respectively, leading to almost 100% and 98.82% effectiveness of A. flavus, respectively. Peanuts harvested from fumigated soil and then stored for 60 d resulted in undetectable levels of aflatoxin B1 (AFB1) compared to unfumigated soil that contained 0.64 ug kg-1 of AFB1, which suggested that soil fumigation can reduce the probability of aflatoxin contamination during peanut storage and showed the potential to increase the safety of peanuts consumed by humans. Further research is planned to determine the practical value of our research in commercial practice.

Fumigation alters the manganese-oxidizing microbial communities to enhance soil manganese availability and increase tomato yield.

Manganese is one of the essential trace elements for plants to maintain normal life activities. Soil fumigation, while effectively controlling soil-borne diseases, can also improve the cycling of soil nutrient elements. MiSeq amplicon sequencing is used to determine the composition of soil microbial communities, and structural equation modeling and the random forest algorithm are employed to conduct a correlation analysis between key manganese-oxidizing microorganisms and soil manganese availability. This experiment investigated the microbial mechanisms behind the observed increase in available manganese in soil after fumigation. The key findings revealed that Bacillus, GeoBacillus, GraciliBacillus, Chungangia, and Pseudoxanthomonas play crucial roles in influencing the variation in soil available manganese content. Fumigation was found to elevate the abundance of Bacillus. Moreover, laccase activity emerged as another significant factor impacting soil manganese availability, showing an indirect correlation with available manganese content and contributing to 58 % of the observed variation in available manganese content. In summary, alterations in the communities of manganese-oxidizing microorganisms following soil fumigation are pivotal for enhancing soil manganese availability.