Lipidomic response of the entomopathogenic fungus Beauveria bassiana to pyrethroids

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.

Antagonistic and additive effect when combining biopesticides against the fall armyworm, Spodoptera frugiperda

Fall armyworm, Spodoptera frugiperda (FAW) is a cosmopolitan crop pest species that has recently become established in sub-Saharan Africa and Southeast Asia. Current FAW control is almost entirely dependent on synthetic pesticides. Biopesticides offer a more sustainable alternative but have limitations. For example, pyrethrum is an effective botanical insecticide with low mammalian toxicity but is highly UV labile, resulting in a rapid loss of efficacy in the field. Beauveria bassiana is an entomopathogenic fungus that is more persistent, but there is a time lag of several days before it causes insect mortality and leads to effective control. The combination of these biopesticides could mitigate their drawbacks for FAW control. Here we evaluated the efficacy of pyrethrum and B. bassiana as individual treatments and in combination against 3rd instar FAW. Four different combinations of these two biopesticides were tested, resulting in an antagonistic relationship at the lowest concentrations of B. bassiana and pyrethrum (1 × 104 conidia mL-1 with 25 ppm) and an additive effect for the other 3 combined treatments (1 × 104 conidia mL-1 with 100 ppm and 1 × 105 conidia mL-1 with 25 ppm and 100 ppm pyrethrum). Additionally, a delay in efficacy from B. bassiana was observed when combined with pyrethrum as well as a general inhibition of growth on agar plates. These results appear to show that this particular combination of biopesticides is not universally beneficial or detrimental to pest control strategies and is dependent on the doses of each biopesticide applied. However, the additive effect shown here at specific concentrations does indicate that combining biopesticides could help overcome the challenges of persistence seen in botanical pesticides and the slow establishment of EPF, with the potential to improve effectiveness of biopesticides for IPM.

Accumulation of pyrethroids induces changes in metabolism of the entomopathogenic fungus Beauveria bassiana-Proteomic and lipidomic background

Advances in the agrochemical industry, such as using plant protection products e.g. pyrethroid insecticides, lead to environmental pollution via the accumulation of toxic compounds in soil. An interesting approach to overcoming this threat is using biopreparations based on entomopathogenic fungi that come into contact with the residues of the insecticides in the environment. The aim of this study was to determine whether the soil-dwelling entomopathogenic fungus Beauveria bassiana ARSEF 2860 is capable of accumulating pyrethroids (λ-cyhalothrin, α-cypermethrin and deltamethrin) and to identify the metabolomics and proteomic implications of this process. In this work, we demonstrated for the first time that the tested fungus accumulated pyrethroids as early as on day 2 of incubation with an average efficiency of 90%. Pyrethroids accumulated in large quantities in the mycelium of B. bassiana induced oxidative stress and interacted differently with the enzymes of the basic metabolic pathways, enzymes associated with the organization of the actin cytoskeleton and cell walls, as well as extracellular enzymes responsible for the infectious abilities (α-cypermethrin caused a 61% decrease in PR1, λ-cyhalothrin - a 31% decrease in PR2, which are proteolytic enzymes with a confirmed role in the infectious process). This study also revealed that the accumulated pyrethroids decreased the activity of phospholipase C, which increased the triacylglycerols/diacylglycerols (TAG/DAG) ratio, especially in mycelium in which α-cypermethrin was accumulated. It should be emphasized that the accumulation of pyrethroids in the environment is not fully understood, and current research suggests that entomopathogenic fungi may be part of the process.

Accelerated PAH Transformation in the Presence of Dye Industry Landfill Leachate Combined with Fungal Membrane Lipid Changes

The ascomycete fungus Nectriella pironii, previously isolated from soil continuously contaminated by dye industry waste, was used for the biodegradation of phenanthrene (PHE), benz[a]anthracene (B[a]A), and benz[a]pyrene (B[a]P). The degradation of polycyclic aromatic hydrocarbons (PAHs) by N. pironii was accelerated in the presence of landfill leachate (LL) collected from the area of fungus isolation. The rate of cometabolic elimination of PHE and B[a]P in the presence of LL was, respectively, 75% and 94% higher than in its absence. LC-MS/MS analysis revealed that PAHs were converted to less-toxic derivatives. The parallel lipidomic study showed changes in membrane lipids, including a significant increase in the content of phosphatidylcholine (PC) (almost double) and saturated phospholipid fatty acids (PLFAs) and a simultaneous reduction (twofold) in the content of phosphatidylethanolamine (PE) and unsaturated PLFAs, which may have promoted the fungus to PHE + LL adaptation. In the presence of PHE, an intense lipid peroxidation (fivefold) was observed, confirming the stabilization of the cell membrane and its extended integrity. Determining the course of elimination and adaptation to harmful pollutants is essential for the design of efficient bioremediation systems in the future.

Lipid Metabolic Disorder Induced by Pyrethroids in Nonalcoholic Fatty Liver Disease of Xenopus laevis

Pyrethroids, an effective and widely used class of pesticides, have attracted considerable concerns considering their frequent detection in environmental matrices. However, their potential health risks to amphibians remain unclear. In our study, female Xenopus laevis were exposed to 0, 0.06, and 0.3 μg/L typical pyrethroid, cis-bifenthrin (cis-BF), for 3 months. Elevated activities of both aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were observed, indicating an ongoing liver injury. Furthermore, exposure to cis-BF led to hyperlipidemia and lipid accumulation in the liver of Xenopus. The targeted lipidomic analysis further revealed that treatment with cis-BF perturbed liver steroid homeostasis, as evidenced by the enriched lipids in the steroid biosynthesis pathway. Consistent with the targeted lipidomic result, treatment with cis-BF changed the liver transcriptome profile with induction of 808 and 1230 differentially expressed genes. Kyoto Encyclopedia of Genes and Genomes analysis underlined the adverse effects of cis-BF exposure on steroid biosynthesis, primary bile acid biosynthesis, and the PPAR signaling pathway in the Xenopus liver. Taken together, our study revealed that exposure to cis-BF at environmentally relevant concentrations resulted in lipid metabolic disorder associated with nonalcoholic fatty liver disease of X. laevis, and our results provided new insight into the potential long-term hazards of pyrethroids.