Nitroreduction of imidacloprid by the actinomycete Gordonia alkanivorans and the stability and acute toxicity of the nitroso metabolite

Recent advances and prospects of neonicotinoid insecticides removal from aquatic environments using biochar: Adsorption and degradation mechanisms

In recent years, neonicotinoid insecticides (NNIs), representing a new era of pest control, have increasingly replaced traditional classes such as organophosphorus compounds, carbamates, and pyrethroids due to their precise targeting and broad-spectrum efficacy. However, the high water solubility of NNIs has led to their pervasion in aquatic ecosystems, raising concerns about potential risks to non-target organisms and human health. Therefore, there is an urgent need for research on remediating NNI contamination in aquatic environments. This study demonstrates that biochar, characterized by its extensive surface area, intricate pore structure, and high degree of aromaticity holds significant promise for removing NNIs from water. The highest reported adsorption capacity of biochar for NNIs stands at 738.0 mg·g-1 with degradation efficiencies reaching up to 100.0 %. This review unveils that the interaction mechanisms between biochar and NNIs primarily involve π-π interactions, electrostatic interactions, pore filling, and hydrogen bonding. Additionally, biochar facilitates various degradation pathways including Fenton reactions, photocatalytic, persulfate oxidations, and biodegradation predominantly through radical (such as SO4-, OH, and O2-) as well as non-radical (such as 1O2 and electrons transfer) processes. This study emphasizes the dynamics of interaction between biochar surfaces and NNIs during adsorption and degradation aiming to elucidate mechanistic pathways involved as well as assess the overall efficacy of biochar in NNI removal. By comparing the identification of degradation products and degradation pathways, the necessity of advanced oxidation process is confirmed. This review highlights the significance of harnessing biochar's potential for mitigating NNI pollution through future application-oriented research and development endeavors, while simultaneously ensuring environmental integrity and promoting sustainable practices.

Non-target influence of imidacloprid residues on grape global metabolome and berry quality with the identification of metabolite biomarkers

This paper illustrates the non-target impact of imidacloprid (IM) residues on the grape global metabolome and biomarker identification with high-resolution mass spectrometry. IM was applied at the recommended dose (SD), and ten times SD (10 RD). The global metabolome analysis revealed that 21 metabolites were up- and down-regulated with IM SD treatment. In 10 RD, 9 metabolites were upregulated, and 28 were downregulated. Pathway enrichment analysis revealed the primary and secondary pathway disruption in grapes. Berry quality was affected with decrease in flavonoids by 32.97% in 10 RD; phenols were reduced by 53.93 in SD, 50.8% in 10 RD. The non-target and target study revealed the degradation of IM in grapes to desnitro-IM and IM-urea which were identified as a potential biomarker for IM residues in grapes, which would benefit the authentication of organic product. Overall, imidacloprid showed a significant impact on the grape metabolome and quality.

Application of pesticide application measures to reduce residue based on the metabolic transfer law of imidacloprid in banana leaves and soil

An investigation of the metabolism and transfer of imidacloprid (IMI) in banana plants and soil was performed using high-resolution mass spectrometry. Results indicated the presence of eight IMI metabolites in soil and leaves that resulted from hydroxylation of the imidazolidine ring, the reduction and loss of nitro groups, and oxidative cleavage of methylene bridges. Six metabolites, including 4/5-hydroxy IMI (4/5-hydroxy), IMI olefin (olefin), and 6-chloronicotinic acid (6-CNA), were detected in the fruits following leaf treatment, while only three were detected after soil treatment. Quantitative analysis showed that the total amount of imidacloprid and its metabolites transferred from leaves to fruits was higher than that transferred from soil to fruits. Therefore, leaf transfer was considered the main means by which IMI and its metabolites transferred to banana fruits. We found that adjuvants tank-mixed with IMI could reduce the total concentration of pesticide transfer from leaves to fruits, especially reducing the amount of metabolites transformed from the reduction and loss of nitro groups and oxidative cleavage of methylene bridges, thus reducing the pesticide residue in fruits and achieving the purpose of reducing the safety risk.

The gut symbiont Sphingomonas mediates imidacloprid resistance in the important agricultural insect pest Aphis gossypii Glover

BACKGROUND

Neonicotinoid insecticides are applied worldwide for the control of agricultural insect pests. The evolution of neonicotinoid resistance has led to the failure of pest control in the field. The enhanced detoxifying enzyme activity and target mutations play important roles in the resistance of insects to neonicotinoid resistance. Emerging evidence indicates a central role of the gut symbiont in insect pest resistance to pesticides. Existing reports suggest that symbiotic microorganisms could mediate pesticide resistance by degrading pesticides in insect pests.

RESULTS

The 16S rDNA sequencing results showed that the richness and diversity of the gut community between the imidacloprid-resistant (IMI-R) and imidacloprid-susceptible (IMI-S) strains of the cotton aphid Aphis gossypii showed no significant difference, while the abundance of the gut symbiont Sphingomonas was significantly higher in the IMI-R strain. Antibiotic treatment deprived Sphingomonas of the gut, followed by an increase in susceptibility to imidacloprid in the IMI-R strain. The susceptibility of the IMI-S strain to imidacloprid was significantly decreased as expected after supplementation with Sphingomonas. In addition, the imidacloprid susceptibility in nine field populations, which were all infected with Sphingomonas, increased to different degrees after treatment with antibiotics. Then, we demonstrated that Sphingomonas isolated from the gut of the IMI-R strain could subsist only with imidacloprid as a carbon source. The metabolic efficiency of imidacloprid by Sphingomonas reached 56% by HPLC detection. This further proved that Sphingomonas could mediate A. gossypii resistance to imidacloprid by hydroxylation and nitroreduction.

CONCLUSIONS

Our findings suggest that the gut symbiont Sphingomonas, with detoxification properties, could offer an opportunity for insect pests to metabolize imidacloprid. These findings enriched our knowledge of mechanisms of insecticide resistance and provided new symbiont-based strategies for control of insecticide-resistant insect pests with high Sphingomonas abundance.

Biochar-derived dissolved black carbon accelerates ferrihydrite microbial transformation and subsequent imidacloprid degradation

The effects of an electron shuttle (dissolved black carbon (DBC) derived from biochar) on the microbial reduction of ferrihydrite and subsequent imidacloprid (IMI) degradation were studied. The results showed that DBC addition enhanced the microbial reduction of Fe(III) in ferrihydrite and increased the quantity of Fe(II) released into the liquid phase. The electron transfer capacity of DBC was significantly influenced by the content of redox-active oxygen-containing functional groups (e.g., quinone, hydroquinone, and polyphenol groups), which was dependent on the pyrolysis temperature. The electrochemical characteristics of DBC resulted in enhanced electron transfer, which promoted Fe(III) reduction and mediated the microbial transformation of ferrihydrite. The microbial transformation of ferrihydrite resulted in the formation of secondary minerals such as siderite and vivianite. The IMI degradation efficiency was related to the Fe(III) reduction rate and the pyrolysis temperature used in DBC production, and the degradation pathways were nitrate reduction and imino hydrolysis induced by the Fe(II) generated from the reduction of Fe(III) in ferrihydrite. The results obtained in this study provide new data for understanding the multifunctional roles of biochar-derived DBC in the redox and transformation processes of iron minerals induced by iron-reducing bacteria, the related biogeochemical cycles of iron and the fate of pollutants.

Multi-omics approach reveals elevated potential of bacteria for biodegradation of imidacloprid

The residual imidacloprid, a widely used insecticide is causing serious environmental concerns. Knowledge of its biodegradation will help in assessing its residual mass in soil. In view of this, a soil microcosm-based study was performed to test the biodegradation potential of Agrobacterium sp. InxBP2. It achieved ∼88% degradation in 20 days and followed the pseudo-first-order kinetics (k = 0.0511 day^-1 and t_1/2=7 days). Whole genome sequencing of Agrobacterium sp. InxBP2 revealed a genome size of 5.44 Mbp with 5179 genes. Imidacloprid degrading genes at loci K7A42_07110 (ABC transporter substrate-binding protein), K7A42_07270 (amidohydrolase family protein), K7A42_07385 (ABC transporter ATP-binding protein), K7A42_16,845 (nitronate monooxygenase family protein), and K7A42_20,660 (FAD-dependent monooxygenase) having sequence and functional similarity with known counterparts were identified. Molecular docking of proteins encoded by identified genes with their respective degradation pathway intermediates exhibited significant binding energies (-6.56 to -4.14 kcal/mol). Molecular dynamic simulation discovered consistent interactions and binding depicting high stability of docked complexes. Proteome analysis revealed differential protein expression in imidacloprid treated versus untreated samples which corroborated with the in-silico findings. Further, the detection of metabolites proved the bacterial degradation of imidacloprid. Thus, results provided a mechanistic link between imidacloprid and associated degradative genes/enzymes of Agrobacterium sp. InxBP2. These findings will be of immense significance in carrying out the lifecycle analysis and formulating strategies for the bioremediation of soils contaminated with insecticides like imidacloprid.

Rapid biodegradation of atrazine by a novel Paenarthrobacter ureafaciens ZY and its effects on soil native microbial community dynamic

An atrazine-utilizing bacterium, designated as ZY, was isolated from agricultural soil and identified as Paenarthrobacter ureafaciens. The P. ureafaciens ZY demonstrated a significant degradation capacity of atrazine, with the degradation efficiency of 12.5 mg L^-1 h^-1 in liquid media (at pH 7, 30°C, and the atrazine level of 100 mg L^-1). The P. ureafaciens ZY contained three atrazine-degrading genes (i.e., trzN, atzB, and atzC) could metabolize atrazine to form cyanuric acid, which showed lower biotoxicity than the parent atrazine as predicted by Ecological Structure Activity Relationships model. A laboratory-scale pot experiment was performed to examine the degradation of atrazine by P. ureafaciens ZY inoculation and investigate its effects on the native microbial communities. The results exhibited that the P. ureafaciens ZY was conductive to the degradation of atrazine, increased the total soil phospholipid fatty acids at the atrazine level of 50, 70, and 100 mg kg^-1. By using high-throughput sequencing analysis, Frateuria, Dyella, Burkholderia-Caballeronia-Paraburkholderia were considered as the most important indigenous atrazine-degrading microorganisms due to their relative abundances were positively correlated with the atrazine degradation rate. In addition, P. ureafaciens ZY also increased the abundance of atrazine-degrading genus Streptomyces and Bacillus, indicating that there may be a synergic relationship between them in the process of atrazine degradation. Our work provides a new insight between inoculums and native microorganisms on the degradation of atrazine.

Biodegradation and Subsequent Toxicity Reduction of Co-contaminants Tribenuron Methyl and Metsulfuron Methyl by a Bacterial Consortium B2R

AllyMax is a widely used herbicide formulation in wheat-rice cropping areas of the world. The residues of its active ingredients, tribenuron methyl (TBM) and metsulfuron methyl (MET), persist in soil and water as co-contaminants, and cause serious threats to nontarget organisms. This study was performed to assess the potential of a bacterial consortium for the degradation and detoxification of TBM and MET individually and as co-contaminants. A bacterial consortium (B2R), comprising Bacillus cereus SU-1, Bacillus velezensis OS-2, and Rhodococcus rhodochrous AQ1, capable of degrading TBM and MET in liquid cultures was developed. Biodegradation of TBM and MET was optimized using the Taguchi design of experiment. Optimum degradation of both TBM and MET was obtained at pH 7 and 37 °C. Regarding media composition, optimum degradation of TBM and MET was obtained in minimal salt medium (MSM) supplemented with glucose, and MSM without glucose, respectively. The consortium simultaneously degraded TBM and MET (94.8 and 80.4%, respectively) in cultures containing the formulation AllyMax, where TBM and MET existed as co-contaminants at 2.5 mg/L each. Mass spectrometry analysis confirmed that during biodegradation, TBM and MET were metabolized into simpler compounds. Onion (Allium cepa) root inhibition and Comet assays revealed that the bacterial consortium B2R detoxified TBM and MET separately and as co-contaminants. The consortium B2R can potentially be used for the remediation of soil and water co-contaminated with TBM and MET.

Biodegradation of imidacloprid: Molecular and kinetic analysis

Imidacloprid (C₉H₁₀ClN₅O₂) is the most widely used insecticide. Its persistence and toxic nature have caused a detrimental effect on living biota. Thus its removal from the contaminated environment has become imperative. The present study aimed to isolate bacterial species from pesticide-contaminated sites and assess their potential for biodegradation of imidacloprid. The 16S rRNA analysis revealed the genetic relatedness of isolates to Sphingobacterium sp., Agrobacterium sp., Pseudomonas sp., and Bacillus sp. Batch biodegradation studies showed that Sphingobacterium sp. and Agrobacterium sp. were the most promising isolates as they degraded 81.0% and 84.9%, respectively, of imidacloprid at the concentration of 95 mg/L via co-metabolism. Kinetic study (V_max/K_s ratio) also suggested the high degradation efficiency of these isolates. Imidacloprid-guanidine (C₉H₁₁ClN₄) was identified as the metabolite. This report highlights the potential of bacteria for imidacloprid degradation and could be utilized for the formulation of strategies for the remediation of imidacloprid contaminated environments.