An Overview of Strobilurin Fungicide Degradation:Current Status and Future Perspective

Proteomic analysis revealed that the oomyceticide phosphite exhibits multi-modal action in an oomycete pathosystem

Phytopathogenic oomycetes constitute some of the most devastating plant pathogens and cause significant crop and horticultural yield and economic losses. The phytopathogen Phytophthora cinnamomi causes dieback disease in native vegetation and several crops. The most commonly used chemical to control P. cinnamomi is the oomyceticide phosphite. Despite its widespread use, the mode of action of phosphite is not well understood and it is unclear whether it targets the pathogen, the host, or both. Resistance to phosphite is emerging in P. cinnamomi isolates and other oomycete phytopathogens. The mode of action of phosphite on phosphite-sensitive and resistant isolates of the pathogen and through a model host was investigated using label-free quantitative proteomics. In vitro treatment of sensitive P. cinnamomi isolates with phosphite hinders growth by interfering with metabolism, signalling and gene expression; traits that are not observed in the resistant isolate. When the model host Lupinus angustifolius was treated with phosphite, proteins associated with photosynthesis, carbon fixation and lipid metabolism in the host were enriched. Increased production of defence-related proteins was also observed in the plant. We hypothesise the multi-modal action of phosphite and present two models constructed using comparative proteomics that demonstrate mechanisms of pathogen and host responses to phosphite. SIGNIFICANCE: Phytophthora cinnamomi is a significant phytopathogenic oomycete that causes root rot (dieback) in a number of horticultural crops and a vast range of native vegetation. Historically, areas infected with phosphite have been treated with the oomyceticide phosphite despite its unknown mode of action. Additionally, overuse of phosphite has driven the emergence of phosphite-resistant isolates of the pathogen. We conducted a comparative proteomic study of a sensitive and resistant isolate of P. cinnamomi in response to treatment with phosphite, and the response of a model host, Lupinus angustifolius, to phosphite and its implications on infection. The present study has allowed for a deeper understanding of the bimodal action of phosphite, suggested potential biochemical factors contributing to chemical resistance in P. cinnamomi, and unveiled possible drivers of phosphite-induced host plant immunity to the pathogen.

Microbial degradation of the benzimidazole fungicide carbendazim by Bacillus velezensis HY-3479

Carbendazim (methyl benzimidazol-2-ylcarbamate: MBC) is a fungicide of the benzimidazole group that is widely used in the cultivation of pepper, ginseng, and many other crops. To remove the remnant carbendazim, many rhizobacteria are used as biodegradation agents. A bacterial strain of soil-isolated Bacillus velezensis HY-3479 was found to be capable of degrading MBC in M9 minimal medium supplemented with 250 mg/L carbendazim. The strain had a significantly higher degradation efficiency compared to the control strain Bacillus subtilis KACC 15590 in high-performance liquid chromatography (HPLC) analysis, and HY-3479 had the best degradation efficiency of 76.99% at 48 h. In gene expression analysis, upregulation of carbendazim-degrading genes (mheI, hdx) was observed in the strain. HY-3479 was able to use MBC as the sole source of carbon and nitrogen, but the addition of 12.5 mM NH4NO3 significantly increased the degradation efficiency. HPLC analysis showed that the degradation efficiency increased to 87.19% when NH4NO3 was added. Relative gene expression of mheI and hdx also increased for samples with NH4NO3 supplementation. The enzyme activity of the carbendazim-degrading enzyme and the 2-aminobenzimidazole-degrading enzyme was found to be highly present in the HY-3479 strain. It is the first reported B. velezensis strain to biodegrade carbendazim (MBC). The biodegradation activity of strain HY-3479 may be developed as a useful means for bioremediation and used as a potential microbial agent in sustainable agriculture.

Strobilurin X acts as an anticancer drug by inhibiting protein synthesis and suppressing mitochondrial respiratory chain activity

PURPOSE

Strobilurins act as antifungal agents by inhibiting the mitochondrial respiratory chain. The cytotoxic activity of strobilurins, focusing on its anticancer activities, has been reported. However, the mechanisms involved in these activities remain unclear.

METHODS

The cytotoxic effects of strobilurin X isolated from the mycelium of Mucidula. venosolamellata were examined in human cancer cell lines (A549 and HeLa) and normal fibroblasts (WI-38).

RESULTS

Strobilurin X significantly decreased the viability of A549 and HeLa cells compared to that in the WI-38 cells after 48 h of exposure. The EC50 values for cytotoxicity in the A549, HeLa, and WI-38 cells were 3.4, 5.4, and 16.8 μg/mL, respectively. Strobilurin X inhibited the mitochondrial respiratory chain and enhanced the release of lactate in the A549 cells. The IC50 value of strobilurin X against the mitochondrial respiratory chain complex III activity was 139.8 ng/mL. The cytotoxicity induced by strobilurin X was not completely rescued after adding uridine, methyl pyruvate, or N-acetyl cysteine. Furthermore, pharmacological approaches demonstrated that strobilurin X failed to modulate the mitogen-activated protein kinase family and phosphoinositide 3-kinase-Akt pathways; alternatively, it suppressed protein synthesis independent of uridine.

CONCLUSION

Strobilurin X induced cytotoxicity by blocking the mitochondrial respiratory chain and suppressing protein synthesis. These findings may aid in the development of novel anticancer drugs using strobilurins.

The Combined Effects of Azoxystrobin and the Biosurfactant-Producing Bacillus sp. Kol B3 against the Phytopathogenic Fungus Fusarium sambucinum IM 6525

This study aimed to evaluate how the combined presence of the synthetic fungicide azoxystrobin (AZ) and the biosurfactant-producing Bacillus sp. Kol B3 influences the growth of the phytopathogenic fungus Fusarium sambucinum IM 6525. The results showed a noticeable increase in antifungal effectiveness when biotic and abiotic agents were combined. This effect manifested across diverse parameters, including fungal growth inhibition, changes in hyphae morphology, fungal membrane permeability and levels of intracellular reactive oxygen species (ROS). In response to the presence of Fusarium and AZ in the culture, the bacteria changed the proportions of biosurfactants (surfactin and iturin) produced. The presence of both AZ and/or Fusarium resulted in an increase in iturin biosynthesis. Only in 72 h old bacterial-fungal co-culture a 20% removal of AZ was noted. In the fungal cultures (with and without the addition of the bacteria), the presence of an AZ metabolite named azoxystrobin free acid was detected in the 48th and 72nd hours of the process. The possible involvement of increased iturin and ROS content in antifungal activity of Bacillus sp. and AZ when used together are also discussed. Biosurfactants were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Microscopy techniques and biochemical assays were also used.

Resistance Risk and Molecular Mechanism of Tomato Wilt Pathogen Fusarium oxysporum f. sp. lycopersici to Pyraclostrobin

Tomato wilt disease caused by Fusarium oxysporum f. sp. lycopersici (Fol) results in a decrease in tomato yield and quality. Pyraclostrobin, a typical quinone outside inhibitor (QoI), inhibits the cytochrome bc1 complex to block energy transfer. However, there is currently limited research on the effectiveness of pyraclostrobin against Fol. In this study, we determined the activity of pyraclostrobin against Fol and found the EC50 values for pyraclostrobin against 100 Fol strains (which have never been exposed to QoIs before). The average EC50 value is 0.3739 ± 0.2413 μg/mL, indicating a strong antifungal activity of pyraclostrobin against Fol, as shown by unimodal curves of the EC50 values. Furthermore, we generated five resistant mutants through chemical taming and identified four mutants with high-level resistance due to the Cytb-G143S mutation and one mutant with medium-level resistance due to the Cytb-G137R mutation. The molecular docking results indicate that the Cytb-G143S or Cytb-G137R mutations of Fol lead to a change in the binding mode of Cytb to pyraclostrobin, resulting in a decrease in affinity. The resistant mutants exhibit reduced fitness in terms of mycelial growth (25 and 30 °C), virulence, and sporulation. Moreover, the mutants carrying the Cytb-G143S mutation suffer a more severe fitness penalty compared to those carrying the Cytb-G137R mutation. There is a positive correlation observed among azoxystrobin, picoxystrobin, fluoxastrobin, and pyraclostrobin for resistant mutants; however, no cross-resistance was detected between pyraclostrobin and pydiflumetofen, prochloraz, or cyazofamid. Thus, we conclude that the potential risk of resistance development in Fol toward pyraclostrobin can be categorized as ranging from low to moderate.

Toxicological impact of strobilurin fungicides on human and environmental health: a literature review

Fungicides are specifically used for controlling fungal infections. Strobilurins, a class of fungicides originating from the mushroom Strobilurus tenacellus, act on the fungal mitochondrial respiratory chain, interrupting the ATP cycle and causing oxidative stress. Although strobilurins are little soluble in water, they have been detected in water samples (such as rainwater and drinking water), indoor dust, and sediments, and they can bioaccumulate in aquatic organisms. Strobilurins are usually absorbed orally and are mainly eliminated via the bile/fecal route and urine, but information about their metabolites is lacking. Strobilurins have low mammalian toxicity; however, they exert severe toxic effects on aquatic organisms. Mitochondrial dysfunction and oxidative stress are the main mechanisms related to the genotoxic damage elicited by toxic compounds, such as strobilurins. These mechanisms alter genes and cause other dysfunctions, including hormonal, cardiac, neurological, and immunological impairment. Despite limitations, we have been able to compile literature information about strobilurins. Many studies have dealt with their toxic effects, but further investigations are needed to clarify their cellular and underlying mechanisms, which will help to find ways to minimize the harmful effects of these compounds.

The looming threat of profenofos organophosphate and microbes in action for their sustainable degradation

Organophosphates are the most extensively used class of pesticides to deal with increasing pest diversity and produce more on limited terrestrial areas to feed the ever-expanding global population. Profenofos, an organophosphate group of non-systematic insecticides and acaricides, is used to combat aphids, cotton bollworms, tobacco budworms, beet armyworms, spider mites, and lygus bugs. Profenofos was inducted into the system as a replacement for chlorpyrifos due to its lower toxicity and half-life. It has become a significant environmental concern due to its widespread presence. It accumulates in various environmental components, contaminating food, water, and air. As a neurotoxic poison, it inhibits acetylcholinesterase receptor activity, leading to dizziness, paralysis, and pest death. It also affects other eukaryotes, such as pollinators, birds, mammals, and invertebrates, affecting ecosystem functioning. Microbes directly expose themselves to profenofos and adapt to these toxic compounds over time. Microbes use these toxic compounds as carbon and energy sources and it is a sustainable and economical method to eliminate profenofos from the environment. This article explores the studies and developments in the bioremediation of profenofos, its impact on plants, pollinators, and humans, and the policies and laws related to pesticide regulation. The goal is to raise awareness about the global threat of profenofos and the role of policymakers in managing pesticide mismanagement.

Exposure to sublethal concentrations of imidacloprid, pyraclostrobin, and glyphosate harm the behavior and fat body cells of the stingless bee Scaptotrigona postica

Pesticide use in agriculture threatens non-target insects such as bees. Considering the ecological and economic relevance of native bees, such as Scaptotrigona postica, and the insufficient studies on the effects of pesticides on their behavior and physiology, improving the current knowledge on this issue is essential. Therefore, this study investigated the sublethal effects of imidacloprid, pyraclostrobin, and glyphosate on the behavior and fat body cells of S. postica. Pesticide ingestion decreased the walking distance and mean velocity of bees compared to the control and solvent control groups. The oenocytes of the control groups were spherical, with central nuclei containing decondensed chromatin, and the trophocytes presented irregular morphology, with cells varying in shape and the cytoplasm filled with vacuoles and granules. However, bees exposed to pesticides showed extensive cytoarchitectural disruption in the fat body, such as vacuolization and shape changes in oenocytes and altered nuclei morphology in trophocytes. Moreover, pesticide exposure increased the number of atypical oenocytes and altered trophocytes, except for the PYR group, which showed a lower number of atypical oenocytes. Caspase-positive labeling significantly increased in all exposed bee groups. Alternatively, TLR4 labeling was significantly decreased in the exposed groups compared to the control groups. There was a significant increase in HSP90 immunolabeling in all exposed groups compared to the control. These findings reinforce the importance of research on the sublethal effects of low pesticide concentrations on key neotropical pollinators and prove that these toxic substances can impair their detoxification and immune defense.

Phytochemicals, Probiotics, Recombinant Proteins: Enzymatic Remedies to Pesticide Poisonings in Bees

The ongoing global decline of bees threatens biodiversity and food safety as both wild plants and crops rely on bee pollination to produce viable progeny or high-quality products in high yields. Pesticide exposure is a major driving force for the decline, yet pesticide use remains unreconciled with bee conservation since studies demonstrate that bees continue to be heavily exposed to and threatened by pesticides in crops and natural habitats. Pharmaceutical methods, including the administration of phytochemicals, probiotics (beneficial bacteria), and recombinant proteins (enzymes) with detoxification functions, show promise as potential solutions to mitigate pesticide poisonings. We discuss how these new methods can be appropriately developed and applied in agriculture from bee biology and ecotoxicology perspectives. As countless phytochemicals, probiotics, and recombinant proteins exist, this Perspective will provide suggestive guidance to accelerate the development of new techniques by directing research and resources toward promising candidates. Furthermore, we discuss practical limitations of the new methods mentioned above in realistic field applications and propose recommendations to overcome these limitations. This Perspective builds a framework to allow researchers to use new detoxification techniques more efficiently in order to mitigate the harmful impacts of pesticides on bees.

The mechanisms of target and non-target resistance to QoIs in Corynespora Cassiicola

Corynespora leaf spot, caused by Corynespora cassiicola, is a foliar disease in cucumber. While the application of quinone outside inhibitors (QoIs) is an effective measure for disease control, it carries the risk of resistance development. In our monitoring of trifloxystrobin resistance from 2008 to 2020, C. cassiicola isolates were categorized into three populations: sensitive isolates (S, 0.01 < EC50 < 0.83 μg/mL), moderately resistant isolates (MR, 1.18 < EC50 < 55.67 μg/mL), and highly resistant isolates (HR, EC50 > 56.98 μg/mL). The resistance frequency reached up to 90% during this period, with an increasing trend observed in the annual average EC50 values of all the isolates. Analysis of the CcCytb gene revealed that both MR and HR populations carried the G143A mutation. Additionally, we identified mitochondrial heterogeneity, with three isolates carrying both G143 and A143 in MR and HR populations. Interestingly, isolates with the G143A mutation (G143A-MR and G143A-HR) displayed differential sensitivity to QoIs. Further experiments involving gene knockout and complementation demonstrated that the major facilitator superfamily (MFS) transporter (CcMfs1) may contribute to the disparity in sensitivity to QoIs between the G143A-MR and G143A-HR populations. However, the difference in sensitivity caused by the CcMfs1 transporter is significantly lower than the differences observed between the two populations. This suggests additional mechanisms contributing to the variation in resistance levels among C. cassiicola isolates. Our study highlights the alarming level of trifloxystrobin resistance in C. cassiicola in China, emphasizing the need for strict prohibition of QoIs use. Furthermore, our findings shed light on the occurrence of both target and non-target resistance mechanisms associated with QoIs in C. cassiicola.

Respiration supports intraphagosomal filamentation and escape of Candida albicans from macrophages

IMPORTANCE

Candida albicans is a leading human fungal pathogen that often causes life-threatening infections in immunocompromised individuals. The ability of C. albicans to transition between yeast and filamentous forms is key to its virulence, and this occurs in response to many host-relevant cues, including engulfment by host macrophages. While previous efforts identified C. albicans genes required for filamentation in other conditions, the genes important for this morphological transition upon internalization by macrophages remained largely enigmatic. Here, we employed a functional genomic approach to identify genes that enable C. albicans filamentation within macrophages and uncovered a role for the mitochondrial ribosome, respiration, and the SNF1 AMP-activated kinase complex. Additionally, we showed that glucose uptake and glycolysis by macrophages support C. albicans filamentation. This work provides insights into the metabolic dueling that occurs during the interaction of C. albicans with macrophages and identifies vulnerabilities in C. albicans that could serve as promising therapeutic targets.

Response of soil phosphatase activity and soil phosphorus fractions to the application of chloropicrin and azoxystrobin in ginger cultivation

BACKGROUND

Soil fumigation can change soil nutrient cycling processes by affecting soil beneficial microorganisms, which is a key issue for soil fertility. However, the effect of combined application of fumigant and fungicide on soil phosphorus (P) availability remains largely unclear. We investigated the effects of the fumigant chloropicrin (CP) and the fungicide azoxystrobin (AZO) on soil phosphatase activity and soil P fractions in ginger production using a 28-week pot experiment with six treatments: control (CK), a single application of AZO (AZO1), double applications of AZO (AZO2), CP-fumigated soil without AZO (CP), CP combined with AZO1 (CP + AZO1) and CP combined with AZO2 (CP + AZO2).

RESULTS

AZO application alone significantly increased the soil labile P fractions (Resin-P + NaHCO3 -Pi + NaOH-Pi) at 9 weeks after planting (WAP) but decreased the soil phosphatase activity at 28 WAP. CP fumigation significantly reduced the soil phosphatase activity but increased the proportions of soil labile P fractions (Resin-P + NaHCO3 -Pi + NaHCO3 -Po) to total P (TP) by 9.0-15.5% throughout the experiment. The combined application of CP and AZO had a synergistic effect on soil phosphatase activity and soil P fractions compared with a single application.

CONCLUSION

Although AZO application and CP fumigation can increase soil available P in the short term, they might negatively affect soil fertility in the long run by inhibiting soil phosphatase activity. Soil microbial activities, especially microorganisms related to P cycling, may be responsible for the variations in soil P availability, but further research is needed. © 2023 Society of Chemical Industry.

Effects of fungicides on fitness and Buchnera endosymbiont density in Aphis gossypii

BACKGROUND

Several agricultural fungicides are known to affect insect pests directly and these effects may be transgenerational and mediated through impacts on endosymbionts, providing opportunities for pest control. The cotton aphid Aphis gossypii is a polyphagous pest that can cause large crop yield losses. Here, we tested the effects of three fungicides, pyraclostrobin, trifloxystrobin and chlorothalonil, on the fitness and Buchnera endosymbiont of A. gossypii.

RESULTS

The formulations of trifloxystrobin and pyraclostrobin, and the active ingredient of pyraclostrobin produced dose-dependent mortality in A. gossypii, whereas there was no dose-dependent mortality for chlorothalonil. The formulations of trifloxystrobin and pyraclostrobin significantly reduced the lifespan and fecundity of A. gossypii, and increased the density of Buchnera in the parental generation but not the (unexposed) F1 . When the active ingredient of pyraclostrobin was tested, the lifespan of the F0 generation was also reduced, but the density of Buchnera was not, indicating that non-insecticidal chemicals in the fungicide formulation may affect the density of the endosymbiont of A. gossypii. There was no transgenerational effect of the active ingredient of pyraclostrobin on the lifespan and Buchnera of (unexposed) F1 .

CONCLUSIONS

Our results suggest that formulations of two strobilurin fungicides have immediate impacts on the fitness of A. gossypii, and chemicals in the formulation impact the density of the primary Buchnera endosymbiont. Our study highlights the potential effects of non-insecticidal chemicals of fungicides on aphid pests and their primary endosymbionts but direct connections between fitness and Buchnera densities remain unclear. © 2023 Society of Chemical Industry.

Discovery of Novel Carboxamide Derivatives Containing Biphenyl Pharmacophore as Potential Fungicidal Agents Used for Resistance Management

Natural products are one of the main sources of drug and agrochemicals discovery. Biphenyls skeleton are ubiquitous structures in many classes of natural products, which indicate extensive biological activities. So, in order to investigate the potential applications for natural biphenyl derivatives, a series of novel carboxamide derivatives with diverse substituent patterns were designed and synthesized based on active pharmacophore from natural biphenyl lignans, and their in vitro antifungal activities against several typical plant pathogens belonging to oomycetes, ascomycete, deuteromycetes, and basidiomycetes were fully investigated. The highly potential compounds were further tested in vivo assay against Botrytis cinerea Pers. of cucumber to demonstrate a practical application for controlling common plant diseases, which indicated four compounds could effectively control the resistant strains of carbendazim, rutamycin, and pyrazolidide. The potential modes of action for compound B12 against B. cinerea were also explored using molecular docking, microscopic technology, and label-free quantitative proteomics analysis. The results show that compound B12 may be a potential novel fungicidal agent used for gray mold resistance control, which can influence the protein synthesis of B. cinerea. These findings can provide a certain theoretical basis for the development of novel biphenyl derivatives as potential green antifungal agents.

Diverse bacteria colonizing leaves and the rhizosphere of lettuce degrade azoxystrobin

Concerns about the possible effects of pesticide residues on both the environment and human health have increased worldwide. Bioremediation by the use of microorganisms to degrade or remove these residues has emerged as a powerful technology. However, the knowledge about the potential of different microorganisms for pesticide degradation is limited. This study focused on the isolation and characterisation of bacterial strains with the potential to degrade the active fungicide ingredient azoxystrobin. Potential degrading bacteria were tested in vitro and in the greenhouse, and the genomes of the best degrading strains were sequenced and analysed. We identified and characterised 59 unique bacterial strains, which were further tested in vitro and in greenhouse trials for their degradation activity. The best degraders from a foliar application trial in the greenhouse were identified as Bacillus subtilis strain MK101, Pseudomonas kermanshahensis strain MK113 and Rhodococcus fascians strain MK144 and analysed by whole genome sequencing. Genome analysis revealed that these three bacterial strains encode several genes predicted to be involved in the degradation of pesticides e.g., benC, pcaG, pcaH, however we could not find any specific gene previously reported to be involved in azoxystrobin degradation e.g., strH. Genome analysis pinpointed to some potential activities involved in plant growth promotion.

Degradation of zearalenone by microorganisms and enzymes

Mycotoxins are toxic metabolites produced by fungi that may cause serious health problems in humans and animals. Zearalenone is a secondary metabolite produced by fungi of the genus Fusarium, widely exists in animal feed and human food. One concern with the use of microbial strains and their enzyme derivatives for zearalenone degradation is the potential variability in the effectiveness of the degradation process. The efficiency of degradation may depend on various factors such as the type and concentration of zearalenone, the properties of the microbial strains and enzymes, and the environmental conditions. Therefore, it is important to carefully evaluate the efficacy of these methods under different conditions and ensure their reproducibility. Another important consideration is the safety and potential side effects of using microbial strains and enzymes for zearalenone degradation. It is necessary to evaluate the potential risks associated with the use of genetically modified microorganisms or recombinant enzymes, including their potential impact on the environment and non-target organisms. Additionally, it is important to ensure that the degradation products are indeed harmless and do not pose any health risks to humans or animals. Furthermore, while the use of microbial strains and enzymes may offer an environmentally friendly and cost-effective solution for zearalenone degradation, it is important to explore other methods such as physical or chemical treatments as well. These methods may offer complementary approaches for zearalenone detoxification, and their combination with microbial or enzyme-based methods may improve overall efficacy. Overall, the research on the biodegradation of zearalenone using microorganisms and enzyme derivatives is promising, but there are important considerations that need to be addressed to ensure the safety and effectiveness of these methods. Development of recombinant enzymes improves enzymatic detoxification of zearalenone to a non-toxic product without damaging the nutritional content. This review summarizes biodegradation of zearalenone using microorganisms and enzyme derivatives to nontoxic products. Further research is needed to fully evaluate the potential of these methods for mitigating the impact of mycotoxins in food and feed.

Enantioselective effect of trifloxystrobin in early-stage zebrafish (Danio rerio) embryos: Cardiac abnormalities impacted by E,E-trifloxystrobin enantiomer

Trifloxystrobin (TFS) is one of the extensively used strobilurin fungicides, which is composed of four enantiomers and its active form is E,E-TFS. In this study, we assess the acute toxicity of four enantiomers, E,E-, E,Z-, Z,E-, and Z,Z-TFS in zebrafish (Danio rerio) embryos. Among the four enantiomers, only E,E-TFS was found to be acutely toxic, with an estimated LC₅₀ value of 0.68 mg/L. Treatment with E,E-TFS resulted in various phenotypic changes in the embryos, including pericardial and yolk-sac edema, spine curvature, and blood pooling. And it shortened the whole body length in the treated embryos by increasing the total intersegmental vessel numbers using a Tg(fli1a:EGFP) zebrafish line. Further study using Tg(cmlc2:EGFP) zebrafish line revealed that E,E-TFS treatment was associated with cardiac malformations, a failure of heart function, and a lowered heartbeat rate at the concentration of 0.25 mg/L. Also, the differential gene expression analysis identified significant down-regulation of vmhc and cacna1c genes encoding ventricular myosin heavy chain and calcium voltage-gated channel subunit alpha 1C, which are crucial for heart development. These results suggest the need for regular monitoring of E,E-TFS enantiomers after field application and further research into their potential chronic effects on environmental organisms.

Visualization of azoxystrobin penetration in wheat leaves using mass microscopy imaging

Fungicides must penetrate the internal tissues of plants to kill pathogenic fungi. Mass spectrometers have been used to confirm this penetration, but conventional mass spectrometric methods cannot distinguish the fungicides in different internal tissues owing to the extraction steps. However, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) can detect the penetration of fungicides into leaf sections through direct analysis of the sample surfaces. Therefore, the objective of this study was to establish a method for visualizing fungicide penetration in wheat leaf cross sections using MALDI-MSI. The penetration of azoxystrobin from the epidermal to the internal tissue of the leaves was observed. Moreover, azoxystrobin accumulates in the cells around the vascular bundle. This study suggests that MSI can be useful for the evaluation of fungicide penetration in plant leaves.

Short-term effects of the strobilurin fungicide dimoxystrobin on zebrafish gills: A morpho-functional study

Strobilurins represent the most widely used class of fungicides nowadays andare considered relatively non-toxic to mammals and birds but highly toxic to aquatic biota. Dimoxystrobin is one of the novel strobilurins, recently included in the 3rd Watch List of the European Commission as available data indicate that it could pose a significant risk to aquatic species. As yet, the number of studies explicitly assessing the impact of this fungicide on terrestrial and aquatic species is extremely low, and the toxic effects of dimoxystrobin on fish have not been reported. Here we investigate for the first time the alterations induced by two environmentally relevant and very low concentrations of dimoxystrobin (6.56 and 13.13 μg/L) in the fish gills. morphological, morphometric, ultrastructural, and functional alterations have been evaluated using zebrafish as a model species. We demonstrated that even short-term exposure (96 h) to dimoxystrobin alters fish gills reducing the surface available for gas exchange and inducing severe alterations encompassing three reaction patterns: circulatory disturbance and both regressive and progressive changes. Furthermore, we revealed that this fungicide impairs the expression of key enzymes involved in osmotic and acid-base regulation (Na⁺/K⁺-ATPase and AQP3) and the defensive response against oxidative stress (SOD and CAT). The information presented here highlights the importance of combining data from different analytical methods for evaluating the toxic potential of currently used and new agrochemical compounds. Our results will also contribute to the discussion on the suitability of mandatory ecotoxicological tests on vertebrates before the introduction on the market of new compounds.

An Exploratory Study of the Metabolite Profiling from Pesticides Exposed Workers

Pesticides constitute a category of chemical products intended specifically for the control and mitigation of pests. With their constant increase in use, the risk to human health and the environment has increased proportionally due to occupational and environmental exposure to these compounds. The use of these chemicals is associated with several toxic effects related to acute and chronic toxicity, such as infertility, hormonal disorders and cancer. The present work aimed to study the metabolic profile of individuals occupationally exposed to pesticides, using a metabolomics tool to identify potential new biomarkers. Metabolomics analysis was carried out on plasma and urine samples from individuals exposed and non-exposed occupationally, using liquid chromatography coupled with mass spectrometry (UPLC-MS). Non-targeted metabolomics analysis, using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) or partial least squares discriminant orthogonal analysis (OPLS-DA), demonstrated good separation of the samples and identified 21 discriminating metabolites in plasma and 17 in urine. The analysis of the ROC curve indicated the compounds with the greatest potential for biomarkers. Comprehensive analysis of the metabolic pathways influenced by exposure to pesticides revealed alterations, mainly in lipid and amino acid metabolism. This study indicates that the use of metabolomics provides important information about complex biological responses.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

Fungal biotechnology: From yesterday to tomorrow

Fungi have been used to better the lives of everyday people and unravel the mysteries of higher eukaryotic organisms for decades. However, comparing progress and development stemming from fungal research to that of human, plant, and bacterial research, fungi remain largely understudied and underutilized. Recent commercial ventures have begun to gain popularity in society, providing a new surge of interest in fungi, mycelia, and potential new applications of these organisms to various aspects of research. Biotechnological advancements in fungal research cannot occur without intensive amounts of time, investments, and research tool development. In this review, we highlight past breakthroughs in fungal biotechnology, discuss requirements to advance fungal biotechnology even further, and touch on the horizon of new breakthroughs with the highest potential to positively impact both research and society.

Pesticides in honey: bibliographic and bibliometric analysis towards matrix quality for consumption

Abstract Honey is a matrix noted for its wide consumption as a sweetener and its anti-inflammatory, antioxidant, and antimicrobial properties; however, its physicochemical quality can be compromised by the presence of toxicants such as pesticides. This review aims to gather recent information on pesticides in honey from the approach to their detection, understanding, and adverse effects on human health. A bibliographic and bibliometric analysis was carried out in academic databases limited to the last five and thirty years, respectively, comprising the keywords “honey”, “pesticides” and their types of pesticides or the agrochemical compound directly. It was found that there are about 30 pesticides detected in honey, in which organochlorine, organophosphate, and neonicotinoid compounds stood out for their concentrations concerning Maximum Residue Levels (MRL). Their physicochemical alteration was not well explored beyond slight variations in brightness and manganese concentration, and its consumption may have repercussions on human reproductive health. It was also determined that there was limited development on the scientific subject seeing that it is important to explore and investigate more on the issue due to the great impact of honey as a product of high consumption at a global level.

Complete genome analysis of sugarcane root associated endophytic diazotroph Pseudomonas aeruginosa DJ06 revealing versatile molecular mechanism involved in sugarcane development

Sugarcane is an important sugar and bioenergy source and a significant component of the economy in various countries in arid and semiarid. It requires more synthetic fertilizers and fungicides during growth and development. However, the excess use of synthetic fertilizers and fungicides causes environmental pollution and affects cane quality and productivity. Plant growth-promoting bacteria (PGPB) indirectly or directly promote plant growth in various ways. In this study, 22 PGPB strains were isolated from the roots of the sugarcane variety GT42. After screening of plant growth-promoting (PGP) traits, it was found that the DJ06 strain had the most potent PGP activity, which was identified as Pseudomonas aeruginosa by 16S rRNA gene sequencing. Scanning electron microscopy (SEM) and green fluorescent protein (GFP) labeling technology confirmed that the DJ06 strain successfully colonized sugarcane tissues. The complete genome sequencing of the DJ06 strain was performed using Nanopore and Illumina sequencing platforms. The results showed that the DJ06 strain genome size was 64,90,034 bp with a G+C content of 66.34%, including 5,912 protein-coding genes (CDSs) and 12 rRNA genes. A series of genes related to plant growth promotion was observed, such as nitrogen fixation, ammonia assimilation, siderophore, 1-aminocyclopropane-1-carboxylic acid (ACC), deaminase, indole-3-acetic acid (IAA) production, auxin biosynthesis, phosphate metabolism, hydrolase, biocontrol, and tolerance to abiotic stresses. In addition, the effect of the DJ06 strain was also evaluated by inoculation in two sugarcane varieties GT11 and B8. The length of the plant was increased significantly by 32.43 and 12.66% and fresh weight by 89.87 and 135.71% in sugarcane GT11 and B8 at 60 days after inoculation. The photosynthetic leaf gas exchange also increased significantly compared with the control plants. The content of indole-3-acetic acid (IAA) was enhanced and gibberellins (GA) and abscisic acid (ABA) were reduced in response to inoculation of the DJ06 strain as compared with control in two sugarcane varieties. The enzymatic activities of oxidative, nitrogen metabolism, and hydrolases were also changed dramatically in both sugarcane varieties with inoculation of the DJ06 strain. These findings provide better insights into the interactive action mechanisms of the P. aeruginosa DJ06 strain and sugarcane plant development.

Degradation of Kresoxim-Methyl in Different Soils: Kinetics, Identification of Transformation Products, and Pathways Using High-Resolution-Mass-Spectrometry-Based Suspect and Non-Target Screening Approaches

This study investigated the degradation of strobilurin fungicide kresoxim-methyl (KM) in three typical agricultural soils from China by aerobic and anaerobic degradation experiments, focusing on degradation kinetics of KM, identification of transformation products (TPs), and prediction of toxicity end points via in silico approaches. KM showed a pronounced biphasic degradation in different soils and could rapidly degrade, with DT₅₀ of <3 days. Four TPs were identified by high-resolution mass spectrometry (HRMS), and three of them have never been reported before. Possible degradation pathways of KM in soil were proposed, including hydrolysis, oxidation, and reduction, and the main mechanism involved in the biodegradation of KM was the hydrolysis of methyl ester regardless of aerobic or anaerobic conditions. The results of toxicity evaluation indicated that some TPs are more toxic than KM and may have a developmental toxicity and mutagenicity, and further risk assessment should be carried out.

Comprehensive study of the effects of strobilurin-based fungicide formulations on Enchytraeus albidus

Excessive application of fungicides in crop fields can cause adverse effects on soil organisms and consequently affect soil properties. Existing knowledge on the effects of strobilurin fungicides has been primarily based on toxicity tests with active ingredients, while the effects of fungicide formulations remain unclear. Therefore, this work aims to provide new data on the effects of three commercial formulations of strobilurin fungicides on the soil organism Enchytraeus albidus. The tested fungicide formulations were Retengo® (pyraclostrobin-PYR), Zato WG 50® (trifloxystrobin-TRI) and Stroby WG® (kresoxim-methyl-KM). In laboratory experiments, multiple endpoints were considered at different time points. The results showed that PYR had the greatest impact on survival and reproduction (LC₅₀ = 7.57 mg_a.i.kg_soil^-1, EC₅₀ = 0.98 mg_a.i.kg_soil^-1), followed by TRI (LC₅₀ = 72.98 mg_a.i.kg_soil^-1, EC₅₀ = 16.93 mg_a.i.kg_soil^-1) and KM (LC₅₀ = 73.12 mg_a.i.kg_soil^-1, EC₅₀ ≥ 30 mg_a.i.kg_soil^-1). After 7 days of exposure, MXR activity was inhibited at the highest concentration of all fungicides tested (6 mg_PYRkg_soil^-1, 15 mg_TRIkg_soil^-1 and 30 mg_KMkg_soil^-1). Furthermore, oxidative stress (induction of SOD, CAT and GST) and lipid peroxidation (increase in MDA) were also observed. In addition, there was a decrease in total available energy after exposure to PYR and KM. Exposure to fungicides resulted in a shift in the proportions of carbohydrates, lipids, and proteins affecting the amount of available energy. In addition to the initial findings on the effects of strobilurin formulations on enchytraeids, the observed results suggest that multiple and long-term exposure to strobilurin formulations in the field could have negative consequences on enchytraeid populations.

Antifungal Activity of Essential Oil and Plant-Derived Natural Compounds against Aspergillus flavus

Aspergillus flavus is a facultative parasite that contaminates several important food crops at both the pre- and post-harvest stages. Moreover, it is an opportunistic animal and human pathogen that causes aspergillosis diseases. A. flavus also produces the polyketide-derived carcinogenic and mutagenic secondary metabolite aflatoxin, which negatively impacts global food security and threatens human and livestock health. Recently, plant-derived natural compounds and essential oils (EOs) have shown great potential in combatting A. flavus spoilage and aflatoxin contamination. In this review, the in situ antifungal and antiaflatoxigenic properties of EOs are discussed. The mechanisms through which EOs affect A. flavus growth and aflatoxin biosynthesis are then reviewed. Indeed, several involve physical, chemical, or biochemical changes to the cell wall, cell membrane, mitochondria, and related metabolic enzymes and genes. Finally, the future perspectives towards the application of plant-derived natural compounds and EOs in food protection and novel antifungal agent development are discussed. The present review highlights the great potential of plant-derived natural compounds and EOs to protect agricultural commodities and food items from A. flavus spoilage and aflatoxin contamination, along with reducing the threat of aspergillosis diseases.

Targeted Method for Quantifying Air-Borne Pesticide Residues from Conventional Seed Coat Treatments to Better Assess Exposure Risk During Maize Planting

Agricultural seed-coat treatments are prone to drift as seed coatings may scuff off and become incorporated into field particles during planting. Vacuum planters release exhaust and kick up field dust, laden with systemic pesticides that blow across the landscape, is taken up, and later expressed in the nectar and pollen of surrounding plants. Offsite movements and nontarget exposure to systemic pesticides need attention and determining how and at what exposure levels pollinators are exposed is of critical importance. Unfortunately, this requires extensive and costly instrumental analyses. Here, we describe dust sampling and a modified, rapid method based on liquid chromatography in tandem with mass spectrometry-based method for quantification of a broad array of agrochemicals in captured dust particles. This method increases ability to detect potential exposure to multiple agrochemicals and allows researchers to better address critical knowledge gaps in the environmental fate, off-target movement, and persistence of conventional seed treatments.

Fungicides have transgenerational effects on Rhopalosiphum padi but not their endosymbionts

BACKGROUND

While several agricultural fungicides are known to directly affect invertebrate pests, including aphids, the mechanisms involved are often unknown. One hypothesis is that fungicides with antibacterial activity suppress bacterial endosymbionts present in aphids which are important for aphid survival. Endosymbiont-related effects are expected to be transgenerational, given that these bacteria are maternally inherited. Here, we test for these associations using three fungicides (chlorothalonil, pyraclostrobin and trifloxystrobin) against the bird cherry-oat aphid, Rhopalosiphum padi, using a microinjected strain that carried both the primary endosymbiont Buchnera and the secondary endosymbiont Rickettsiella.

RESULTS

We show that the fungicide chlorothalonil did not cause an immediate effect on aphid survival, whereas both strobilurin fungicides (pyraclostrobin and trifloxystrobin) decreased survival after 48 h exposure. However, chlorothalonil substantially reduced the lifespan and fecundity of the F1 generation. Trifloxystrobin also reduced the lifespan and fecundity of F1 offspring, however, pyraclostrobin did not affect these traits. None of the fungicides consistently altered the density of Buchnera or Rickettsiella in whole aphids.

CONCLUSIONS

Our results suggest fungicides have sublethal impacts on R. padi that are not fully realized until the generation after exposure, and these sublethal impacts are not associated with the density of endosymbionts harbored by R. padi. However, we cannot rule out other effects of fungicides on endosymbionts that might influence fitness, like changes in their tissue distribution. We discuss these results within the context of fungicidal effects on aphid suppression across generations and point to potential field applications. © 2022 Society of Chemical Industry.

Isolation, characterization and application of the epoxiconazole-degrading strain Pseudomonas sp. F1 in a soil-vegetable system

Epoxiconazole (EPX) has a long half-life in soil and causes various toxicological effects in both the ecosystem and mammals. In this study, eight strains of bacteria capable of degrading EPX were isolated from pesticide-contaminated soil, with strain F1 showing the best effect. This strain was identified as Pseudomonas sp. by 16S rRNA gene sequencing and physiological-biochemical analyses. Our results indicated that strain F1 has a high capacity to degrade EPX, removing 92.1% of EPX within 6 days. The temperature and pH were the two most important environmental factors affecting EPX degradation, followed by substrate concentration and inoculum dose. In addition, strain F1 has a high capacity to promote EPX degradation in soils, with a lower t_1/2 value (2.64 d) in F1-inoculated soil compared to the control (t_1/2 = 96.3 d) without strain F1. The strain could efficiently colonize rhizosphere soil and enhance degradation of EPX, leading to a significant decrease in the accumulation and translocation of EPX in vegetables, thereby alleviating the effects of EPX-induced stress on plants. Moreover, we observed that strain F1-gfp was able to colonize the roots, stems and leaves of Brassica rapa var. chinensis. Such colonization may play a role in the efficient degradation of EPX within plants. To our knowledge, this is the first study to demonstrate biodegradation of EPX in a soil-vegetable system using an EPX-degrading bacterium. This study indicates that strain F1 is a promising candidate for simultaneous bioremediation of soil contaminated with EPX and safe food production.

Preparation of metal-organic framework @molecularly imprinted polymers for extracting strobilurin fungicides from agricultural products

The core-shell metal-organic framework coated with molecularly imprinted polymers (ZIF-8@MIPs) were successfully synthesized by surface imprinting technique, and applied as adsorbents for solid-phase extraction of strobilurin fungicides. The obtained hybrid complex was characterized in detail, and their adsorbing and recognition performance were evaluated. The results showed that ZIF-8@MIPs presented typically core-shell structure with MIP shell (about 20 nm), and exhibited larger adsorption capacity (102.5 mg g^-1) and fast adsorption ability (only 5 min). Under the optimized conditions, a sensitive, efficient and reliable method for determining six strobilurin fungicides in different agricultural products based on ZIF-8@MIPs coupling with high performance liquid chromatography-tandem mass spectrometry was established. This method showed good linearity with correlation coefficients higher than 0.9990. With spiked at three different concentration levels in agricultural products (apple, pear, banana, Chinese cabbage, cabbage, cucumber), the good recoveries (83.5-129.0%) with relative standard deviations from 0.5 to 10.2% were obtained. The limit of detections and the limit of quantifications were 0.01-1.12 ng g^-1 and 0.03-3.73 ng g^-1, respectively. Those results demonstrated good potential application of ZIF-8@MIPs for enriching and separating trace strobilurin fungicides in agricultural samples.

Bioremediation of quinclorac injury on tobacco by a rhizosphere bacterium

The presence of herbicides residues in soil represents a serious problem for agriculture. Quinclorac is a common herbicide applied in rice field, but its residue can cause abnormal growth in successive crop of tobacco in Southern China. Remediation by microorganisms is considered to be an environmentally friendly method to remove such pollutants injury. The aims of this study were to obtain quinclorac remediation isolates and to investigate the possible mechanism(s) of remediation. Six bacterial isolates were obtained from rhizosphere of rice-tobacco rotation fields, and were found to be capable of degrading quinclorac on a mineral salt medium (MSM), with degradation efficiency ranging from 2.1 to 23.7%. Among these isolates, J5 had the highest degradation efficiency, and was identified as Klebsiella variicola based on phylogenetic analyses and a metabolic profile generating by Biolog GEN III system. Bioremediation of quinclorac injury was confirmed using pot assays with tobacco, in which J5 reversed the detrimental effect of quinclorac on leaf area, leaf number, and plant height. The J5 isolate also seemed to promote plant growth, in terms of tobacco seedling growth and seed germination, which were 2.2 times and 1.6 times higher compared to untreated control, respectively. The mechanisms of plant growth promoting (PGP) traits were found to involve nitrogen-fixing, indole-3-acetic acid (IAA) production, and phosphate solubilization ability. In addition, proteomic analysis and relative quantitative PCR revealed an elevated level of 4-hydroxyphenylacetate 3-monooxygenase (HPMO) in quinclorac-treated J5, suggesting that this enzyme may play an important role in quinclorac remediation. This study showed that the J5 isolate could be exploited to not only assist in soil remediation due to quinclorac residue issues but also promote tobacco growth.

Identifying novel drugs with new modes of action for neglected tropical fungal skin diseases (fungal skinNTDs) using an Open Source Drug discovery approach

INTRODUCTION

The three fungal skin neglected tropical diseases (NTD) mycetoma, chromoblastomycosis and sporotrichosis currently lack prioritization and support to establish drug discovery programs in search for novel treatment options. This has made the efforts to identify novel drugs for these skinNTDs fragmented.

AREAS COVERED

To help escalate the discovery of novel drugs to treat these fungal skinNTDs, the authors have prepared an overview of the compounds with activity against fungal skinNTDs by analyzing data from individual drug discovery studies including those performed on the Medicines for Malaria Venture (MMV) open access boxes.

EXPERT OPINION

The authors were unable to identify studies in which causative agents of all three skinNTDs were included, indicating that an integrated approach is currently lacking. From the currently available data, the azoles and iodoquinol were the only compounds with activity against causative agents from the three different fungal skinNTDs. Fungal melanin inhibition enhanced the activity of antifungal agents. For mycetoma, the fenarimols, aminothiazoles and benzimidazole carbamates are currently being investigated in the MycetOS initiative. To come to a more integrated approach to identify drugs active against all three fungal skinNTDs, compounds made in the MycetOS initiative could also be explored for chromoblastomycosis and sporotrichosis.

Microbial Degradation of Aldrin and Dieldrin: Mechanisms and Biochemical Pathways

As members of the organochlorine group of insecticides, aldrin and dieldrin are effective at protecting agriculture from insect pests. However, because of excessive use and a long half-life, they have contributed to the major pollution of the water/soil environments. Aldrin and dieldrin have been reported to be highly toxic to humans and other non-target organisms, and so their use has gradually been banned worldwide. Various methods have been tried to remove them from the environment, including xenon lamps, combustion, ion conversion, and microbial degradation. Microbial degradation is considered the most promising treatment method because of its advantages of economy, environmental protection, and convenience. To date, a few aldrin/dieldrin-degrading microorganisms have been isolated and identified, including Pseudomonas fluorescens, Trichoderma viride, Pleurotus ostreatus, Mucor racemosus, Burkholderia sp., Cupriavidus sp., Pseudonocardia sp., and a community of anaerobic microorganisms. Many aldrin/dieldrin resistance genes have been identified from insects and microorganisms, such as Rdl, bph, HCo-LGC-38, S2-RDL^A302S, CSRDL1A, CSRDL2S, HaRdl-1, and HaRdl-2. Aldrin degradation includes three pathways: the oxidation pathway, the reduction pathway, and the hydroxylation pathway, with dieldrin as a major metabolite. Degradation of dieldrin includes four pathways: oxidation, reduction, hydroxylation, and hydrolysis, with 9-hydroxydieldrin and dihydroxydieldrin as major products. Many studies have investigated the toxicity and degradation of aldrin/dieldrin. However, few reviews have focused on the microbial degradation and biochemical mechanisms of aldrin/dieldrin. In this review paper, the microbial degradation and degradation mechanisms of aldrin/dieldrin are summarized in order to provide a theoretical and practical basis for the bioremediation of aldrin/dieldrin-polluted environment.

Mixed Contaminants: Occurrence, Interactions, Toxicity, Detection, and Remediation

The ever-increasing rate of pollution has attracted considerable interest in research. Several anthropogenic activities have diminished soil, air, and water quality and have led to complex chemical pollutants. This review aims to provide a clear idea about the latest and most prevalent pollutants such as heavy metals, PAHs, pesticides, hydrocarbons, and pharmaceuticals—their occurrence in various complex mixtures and how several environmental factors influence their interaction. The mechanism adopted by these contaminants to form the complex mixtures leading to the rise of a new class of contaminants, and thus resulting in severe threats to human health and the environment, has also been exhibited. Additionally, this review provides an in-depth idea of various in vivo, in vitro, and trending biomarkers used for risk assessment and identifies the occurrence of mixed contaminants even at very minute concentrations. Much importance has been given to remediation technologies to understand our current position in handling these contaminants and how the technologies can be improved. This paper aims to create awareness among readers about the most ubiquitous contaminants and how simple ways can be adopted to tackle the same.

Nanobioremediation: A sustainable approach for the removal of toxic pollutants from the environment

In recent years, the proportion of organic and inorganic contaminants has increased rapidly due to growing human interference and represents a threat to ecosystems. The removal of these toxic pollutants from the environment is a difficult task. Physical, chemical and biological methods are implemented for the degradation of toxic pollutants from the environment. Among existing technologies, bioremediation in combination with nanotechnology is the most promising and cost-effective method for the removal of pollutants. Numerous studies have shown that exceptional characteristics of nanomaterials such as improved catalysis and adsorption properties as well as high reactivity have been subjects of great interest. There is an emerging trend of employing bacterial, fungal and algal cultures and their components, extracts or biomolecules as catalysts for the sustainable production of nanomaterials. They can serve as facilitators in the bioremediation of toxic compounds by immobilizing or inducing the synthesis of remediating microbial enzymes. Understanding the association between microorganisms, contaminants and nanoparticles (NPs) is of crucial importance. In this review, we focus on the removal of toxic pollutants using the cumulative effects of nanoparticles with microbial technology and their applications in different domains. Besides, we discuss how this novel nanobioremediation technique is significant and contributes towards sustainability.

Overarching issues on relevant pesticide transformation products in the aquatic environment: A review

The intensification of agricultural production during the last decades has forced the rapid increase in the use of pesticides that finally end up in the aquatic environment. Albeit well-documented, pesticides continue to raise researchers' attention, because of their potential adverse impacts on the environment and, inevitably, humans. Once entering the aquatic bodies, pesticides undergo biotic and abiotic processes, resulting in transformation products (TPs) that sometimes are even more toxic than the parent compounds. A substantial shift of the scientific interest in the TPs of pesticides has been observed since their environmental fate, occurrence and toxicity is still in its formative stage. In an ongoing effort to expand the existing knowledge on the topic, several interesting works have been performed mostly in European countries, such as France, Germany, Italy, Switzerland, Greece, and Spain that counts the highest number of relevant publications. Pesticide TPs have been also studied to a lesser extent in Asia, North and South America. To this end, the main objective of this review is to delineate the global occurrence, fate, toxicity as well as the analytical challenges related to pesticide TPs in surface, ground, and wastewaters, with the view to contribute to a better understanding of the environmental problems related with TPs formation. The concentration levels of the TPs, ranging from the low ng/L to high μg/L scale and distributed worldwide. Ultimately, an attempt to predict the acute and chronic toxicity of TPs has been carried out with the aid of an in-silico approach based on ECOSAR, revealing increased chronic toxicity for the majority of the identified TPs, despite the change they underwent, while a small portion of them presented serious acute toxicity values.

Carboxylesterases from bacterial enrichment culture degrade strobilurin fungicides

Strobilurin fungicides are a class of persistent fungicides frequently detected in the environment. Microbes can effectively degrade strobilurins, but the mechanisms are complex and diverse. Compared with isolated strains, bacterial consortia are more robust in terms of the degradation of multiple pollutants. The enrichment culture XS19 is a group of bacterial strains enriched from soil and degrades six strobilurins at 50 mg/L within 8 d, including azoxystrobin, picoxystrobin, trifloxystrobin, kresoxim-methyl, pyraclostrobin and enestroburin. LC-Q-TOF-MS analysis confirmed that XS19 can demethylate these strobilurins via hydrolysis of the methyl ester group. Analysis of the bacterial communities suggested that Pseudomonas (69.8%), Sphingobacterium (21.2%), Delftia (6.3%), and Achromobacter (1.6%) spp. were highly associated with the removal of strobilurins in the system. Metagenomics-based comprehensive analysis of XS19 suggested that carboxylesterases in Pseudomonas and Sphingobacterium play a central role in the catabolism of strobilurins. Moreover, the carboxylesterase inhibitor bis-p-nitrophenyl phosphate inhibited the degradation activity of strobilurins in XS19. This work proved that XS19 or carboxylesterases can effectively hydrolyze strobilurins, providing a reliable bioremediation paradigm.

Pyraclostrobin Removal in Pilot-Scale Horizontal Subsurface Flow Constructed Wetlands and in Porous Media Filters

Pyraclostrobin is a fungicide extensively used for the control of various fungal diseases and is frequently detected in environmental samples. Natural systems, such as constructed wetlands (CWs) and gravity filters, are effective and environmentally friendly treatment systems, which can reduce or eliminate pesticides from the environment. The aim of this study was to investigate the capacity of two pilot-scale CWs (porous media: cobbles and fine gravel, planted with Phragmites australis) and six gravity filters (filling material: bauxite, carbonate gravel and zeolite) to remove pyraclostrobin from polluted water originating from spraying equipment rinsing sites. For this, experiments were conducted to test the performance of the above natural systems in removing this fungicide. The results showed that the mean percent pyraclostrobin removal efficiencies for cobbles and fine gravel CW units were 56.7% and 75.2%, respectively, and the mean percent removals for HRTs of 6 and 8 days were 68.7% and 62.8%, respectively. The mean removal efficiencies for the bauxite, carbonate gravel and zeolite filter units were 32.5%, 36.7% and 61.2%, respectively, and the mean percent removals for HRTs 2, 4 and 8 days were 39.9%, 43.4% and 44.1%, respectively. Regarding the feeding strategy, the mean removal values of pyraclostrobin in gravity filter units were 43.44% and 40.80% for continuous and batch feeding, respectively. Thus, these systems can be used in rural areas for the treatment of spraying equipment rinsing water.

Investigating Fungal Biosynthetic Pathways Using Pichia pastoris as a Heterologous Host

Fungal natural products have extensive biological activities, and thus have been largely commercialized in the pharmaceutical, agricultural, and food industries. Recently, heterologous expression has become an irreplaceable technique to functionalize fungal biosynthetic gene clusters and synthesize fungal natural products in various chassis organisms. This chapter describes the general method of using Pichia pastoris as a chassis host to investigate fungal biosynthetic pathways.

Azoxystrobin Impairs Neuronal Migration and Induces ROS Dependent Apoptosis in Cortical Neurons

Fungicides often cause genotoxic stress and neurodevelopmental disorders such as autism (ASD). Fungicide-azoxystrobin (AZOX) showed acute and chronic toxicity to various organisms, and remained a concern for ill effects in developing neurons. We evaluated the neurotoxicity of AZOX in developing mouse brains, and observed prenatal exposure to AZOX reduced neuronal viability, neurite outgrowth, and cortical migration process in developing brains. The 50% inhibitory concentration (IC50) of AZOX for acute (24 h) and chronic (7 days) exposures were 30 and 10 μM, respectively. Loss in viability was due to the accumulation of reactive oxygen species (ROS), and inhibited neurite outgrowth was due to the deactivation of mTORC1 kinase activity. Pretreatment with ROS scavenger- N-acetylcysteine (NAC) reserved the viability loss and forced activation of mTORC1 kinase revived the neurite outgrowth in AZOX treated neurons. Intra-amniotic injection of AZOX coupled with in utero electroporation of GFP-labelled plasmid in E15.5 mouse was performed and 20 mg/kg AZOX inhibited radial neuronal migration. Moreover, the accumulation of mitochondria was significantly reduced in AZOX treated primary neurons, indicative of mitochondrial deactivation and induction of apoptosis, which was quantified by Bcl2/Bax ratio and caspase 3 cleavage assay. This study elucidated the neurotoxicity of AZOX and explained the possible cure from it.

Biodegradation of fipronil: current state of mechanisms of biodegradation and future perspectives

Fipronil is a broad-spectrum phenyl-pyrazole insecticide that is widely used in agriculture. However, in the environment, its residues are toxic to aquatic animals, crustaceans, bees, termites, rabbits, lizards, and humans, and it has been classified as a C carcinogen. Due to its residual environmental hazards, various effective approaches, such as adsorption, ozone oxidation, catalyst coupling, inorganic plasma degradation, and microbial degradation, have been developed. Biodegradation is deemed to be the most effective and environmentally friendly method, and several pure cultures of bacteria and fungi capable of degrading fipronil have been isolated and identified, including Streptomyces rochei, Paracoccus sp., Bacillus firmus, Bacillus thuringiensis, Bacillus spp., Stenotrophomonas acidaminiphila, and Aspergillus glaucus. The metabolic reactions of fipronil degradation appear to be the same in different bacteria and are mainly oxidation, reduction, photolysis, and hydrolysis. However, the enzymes and genes responsible for the degradation are somewhat different. The ligninolytic enzyme MnP, the cytochrome P450 enzyme, and esterase play key roles in different strains of bacteria and fungal. Many unanswered questions exist regarding the environmental fate and degradation mechanisms of this pesticide. The genes and enzymes responsible for biodegradation remain largely unexplained, and biomolecular techniques need to be applied in order to gain a comprehensive understanding of these issues. In this review, we summarize the literature on the degradation of fipronil, focusing on biodegradation pathways and identifying the main knowledge gaps that currently exist in order to inform future research. KEY POINTS: • Biodegradation is a powerful tool for the removal of fipronil. • Oxidation, reduction, photolysis, and hydrolysis play key roles in the degradation of fipronil. • Possible biochemical pathways of fipronil in the environment are described.

Insights into the microbial degradation and biochemical mechanisms of carbamates

Carbamate compounds are commonly applied in agricultural sectors as alternative options to the recalcitrant organochlorine pesticides due to their easier breakdown and less persistent nature. However, the large-scale use of carbamates also leads to toxic environmental residues, causing severe toxicity in various living systems. The toxic effects of carbamates are due to their inhibitor activity against the acetylchlolinesterase enzyme. This enzyme is crucial for neurotransmission signaling in living beings. Hence, from the environmental point of view, the elimination of carbamates is a worldwide concern and priority. Microbial technology can be deliberated as a potential tool that can work efficiently and as an ecofriendly option for the dissipation of carbamate insecticides from contaminated environments by improving biodegradation processes via metabolic activities of microorganisms. A variety of bacterial and fungal species have been isolated and characterized and are capable of degrading a broad range of carbamates in soil and water environments. In addition, microbial carbamate hydrolase genes (mcd, cehA, cahA, cfdJ, and mcbA) were strongly implicated in the evolution of new metabolic functions and carbamate hydrolase enzymes. However, the accurate localization and appropriate functions of carbamate hydrolase enzymes/genes are very limited. To explore the information on the degradation routes of carbamates and promote the application of biodegradation, a study of molecular techniques is required to unlock insights regarding the degradation specific genes and enzymes. Hence, this review discusses the deep understanding of carbamate degradation mechanisms with microbial strains, metabolic pathways, molecular mechanisms, and their genetic basis in degradation.

Emerging Strategies for the Bioremediation of the Phenylurea Herbicide Diuron

Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its widespread presence in soil, sediment, and aquatic environments, which poses a threat to non-target crops, animals, humans, and ecosystems. Therefore, the removal of DUR from contaminated environments has been a hot topic for researchers in recent decades. Bioremediation seldom leaves harmful intermediate metabolites and is emerging as the most effective and eco-friendly strategy for removing DUR from the environment. Microorganisms, such as bacteria, fungi, and actinomycetes, can use DUR as their sole source of carbon. Some of them have been isolated, including organisms from the bacterial genera Arthrobacter, Bacillus, Vagococcus, Burkholderia, Micrococcus, Stenotrophomonas, and Pseudomonas and fungal genera Aspergillus, Pycnoporus, Pluteus, Trametes, Neurospora, Cunninghamella, and Mortierella. A number of studies have investigated the toxicity and fate of DUR, its degradation pathways and metabolites, and DUR-degrading hydrolases and related genes. However, few reviews have focused on the microbial degradation and biochemical mechanisms of DUR. The common microbial degradation pathway for DUR is via transformation to 3,4-dichloroaniline, which is then metabolized through two different metabolic pathways: dehalogenation and hydroxylation, the products of which are further degraded via cooperative metabolism. Microbial degradation hydrolases, including PuhA, PuhB, LibA, HylA, Phh, Mhh, and LahB, provide new knowledge about the underlying pathways governing DUR metabolism. The present review summarizes the state-of-the-art knowledge regarding (1) the environmental occurrence and toxicity of DUR, (2) newly isolated and identified DUR-degrading microbes and their enzymes/genes, and (3) the bioremediation of DUR in soil and water environments. This review further updates the recent knowledge on bioremediation strategies with a focus on the metabolic pathways and molecular mechanisms involved in the bioremediation of DUR.

Potential aquatic environmental risks of trifloxystrobin: Enhancement of virus susceptibility in zebrafish through initiation of autophagy

Chronic pollution in aquatic ecosystems can lead to many adverse effects, including a greater susceptibility to pathogens among resident biota. Trifloxystrobin (TFS) is a strobilurin fungicide widely used in Asia to control soybean rust. However, it has the potential to enter aquatic ecosystems, where it may impair fish resistance to viral infections. To explore the potential environmental risks of TFS, we characterized the antiviral capacities of fish chronically exposed to TFS and subsequently infected with spring viraemia of carp virus (SVCV). Although TFS exhibited no significant cytotoxicity at the tested environmental concentrations during viral challenge, SVCV replication increased significantly in a time-dependent manner within epithelioma papulosum cyprini (EPC) cells and zebrafish exposed to 25 μg/L TFS. Results showed that the highest viral load was more than 100-fold that of the controls. Intracellular biochemical assays indicated that autophagy was induced by TFS, and associated changes included an increase in autophagosomes, conversion of LC3-II, accumulation of Beclin-1, and degradation of P62 in EPC cells and zebrafish. In addition, TFS markedly decreased the expression and phosphorylation of mTOR, indicating that activation of TFS may be associated with the mTOR-mediated autophagy pathway. This study provides new insights into the mechanism of the immunosuppressive effects of TFS on non-target aquatic hosts and suggests that the existence of TFS in aquatic environments may contribute to outbreaks of viral diseases.

Non-target Impact of Dinotefuran and Azoxystrobin on Soil Bacterial Community and Nitrification

Pesticides to protect crops from pests are subject to rigorous risk assessment before registration in Japan. However, further information needs to be collected regarding the assessment of impacts on the natural environment. In particular, nitrifying bacteria play a role in converting ammonium salts to nitrates in soil. However, there is limited research covering the effects of insecticides on nitrification, despite several fungicides and herbicides have an inhibitory effect on nitrifying bacteria. Therefore, we investigated the effect of pesticides on the nitrification when applied to soil. The application of both pesticides promoted ammonia oxidation, and suppressed nitrite oxidation in a high-concentration treatment of dinotefuran. In addition, it was clarified that the diversity and species richness of soil bacteria was significantly reduced when the pesticides were applied to the soil, and that the specific soil bacteria (Metyhlotenera spp.) dominated the application of the pesticides.

Azoxystrobin amine: A novel azoxystrobin degradation product from Bacillus licheniformis strain TAB7

Azoxystrobin (AZ) is a broad-spectrum synthetic fungicide widely used in agriculture globally. However, there are concerns about its fate and effects in the environment. It is reportedly transformed into azoxystrobin acid as a major metabolite by environmental microorganisms. Bacillus licheniformis strain TAB7 is used as a compost deodorant in commercial compost and has been found to degrade some phenolic and agrochemicals compounds. In this article, we report its ability to degrade azoxystrobin by novel degradation pathway. Biotransformation analysis followed by identification by electrospray ionization-mass spectrometry (MS), high-resolution MS, and nuclear magnetic resonance spectroscopy identified methyl (E)-3-amino-2-(2-((6-(2-cyanophenoxy)pyrimidin-4-yl)oxy)phenyl)acrylate, or (E)-azoxystrobin amine in short, and (Z) isomers of AZ and azoxystrobin amine as the metabolites of (E)-AZ by TAB7. Bioassay testing using Magnaporthe oryzae showed that although 40 μg/mL of (E)-AZ inhibited 59.5 ± 3.5% of the electron transfer activity between mitochondrial Complexes I and III in M. oryzae, the same concentration of (E)-azoxystrobin amine inhibited only 36.7 ± 15.1% of the activity, and a concentration of 80 μg/mL was needed for an inhibition rate of 56.8 ± 7.4%, suggesting that (E)-azoxystrobin amine is less toxic than the parent compound. To our knowledge, this is the first study identifying azoxystrobin amine as a less-toxic metabolite from bacterial AZ degradation and reporting on the enzymatic isomerization of (E)-AZ to (Z)-AZ, to some extent, by TAB7. Although the fate of AZ in the soil microcosm supplemented with TAB7 will be needed, our findings broaden our knowledge of possible AZ biotransformation products.

Emerging Technologies for Degradation of Dichlorvos: A Review

Dichlorvos (O,O-dimethyl O-(2,2-dichlorovinyl)phosphate, DDVP) is a widely acknowledged broad-spectrum organophosphorus insecticide and acaracide. This pesticide has been used for more than four decades and is still in strong demand in many developing countries. Extensive application of DDVP in agriculture has caused severe hazardous impacts on living systems. The International Agency for Research on Cancer of the World Health Organization considered DDVP among the list of 2B carcinogens, which means a certain extent of cancer risk. Hence, removing DDVP from the environment has attracted worldwide attention. Many studies have tested the removal of DDVP using different kinds of physicochemical methods including gas phase surface discharge plasma, physical adsorption, hydrodynamic cavitation, and nanoparticles. Compared to physicochemical methods, microbial degradation is regarded as an environmentally friendly approach to solve several environmental issues caused by pesticides. Till now, several DDVP-degrading microbes have been isolated and reported, including but not limited to Cunninghamella, Fusarium, Talaromyces, Aspergillus, Penicillium, Ochrobium, Pseudomonas, Bacillus, and Trichoderma. Moreover, the possible degradation pathways of DDVP and the transformation of several metabolites have been fully explored. In addition, there are a few studies on DDVP-degrading enzymes and the corresponding genes in microorganisms. However, further research relevant to molecular biology and genetics are still needed to explore the bioremediation of DDVP. This review summarizes the latest development in DDVP degradation and provides reasonable and scientific advice for pesticide removal in contaminated environments.

Binding interaction of glyphosate with glyphosate oxidoreductase and C-P lyase: Molecular docking and molecular dynamics simulation studies

Widespread application of glyphosate poses a threat to living organisms. Microbial strains are able to degrade glyphosate via contrasting metabolic pathways with the help of enzymes. Glyphosate oxidoreductase (GOX) and C-P lyase are the key enzymes for the biodegradation of glyphosate and its intermediate metabolite aminomethylphosphonic acid (AMPA) in microbes. The microbial degradation of glyphosate has been reported, but the underlying molecular mechanism is still unclear. Therefore, in this study, the interaction mechanism of GOX and C-P lyase with glyphosate and AMPA were investigated by using molecular docking and molecular dynamics (MD) simulations. The results indicate that glyphosate contacts with the active site of GOX and C-P lyase by hydrogen bonds as well as hydrophobic and van der Waals interactions in aqueous solution to maintain its stability. The presence of glyphosate and AMPA in the active site significantly changes the conformation of GOX and C-P lyase. The results of the MD simulations confirm that GOX and C-P lyase complexes are stable during the catalytic reaction. This study offers a molecular level of understanding of the expression and function of GOX and C-P lyase for the bioremediation of glyphosate.