Trichlorfon is an organic phosphorus pesticide used to control different parasitic infections in aquaculture. The repeated, excessive use of trichlorfon can result in environmental pollution, thus affecting human health. This study aimed to determine the effects of different concentrations of trichlorfon (0, 0.1, 0.5 and 1.0 mg/L) on the intestinal barrier, oxidative stress, inflammatory response and intestinal microbiome of common carp. Trichlorfon exposure significantly reduced the height of intestinal villus and decreased the expression levels of tight junction genes, such as claudin-2, occludin and ZO-1, in common carp. Moreover, the activities of antioxidant enzymes, such as CAT, SOD and GSH-Px, exhibited a decreasing trend with increasing trichlorfon concentrations, while the contents of MDA and ROS elevated in the intestinal tissues of common carp. The mRNA and protein levels of pro-inflammatory cytokines TNF-α and IL-1β were significantly upregulated by trichlorfon exposure. The level of anti-inflammatory cytokine TGF-β was remarkably higher in 1.0 mg/L trichlorfon treatment group compared to control group. In addition, the results demonstrated that trichlorfon exposure could affect the microbiota community composition and decreased the community diversity in the gut of common carp. Notably, the proportions of some probiotic bacteria, namely, Lactobacillus, Bifidobacterium and Akkermansia, were observed to be reduced after trichlorfon exposure. In summary, the findings of this study indicate that exposure to different concentrations of trichlorfon can damage intestinal barrier, induce intestinal oxidative damage, trigger inflammatory reaction and alter gut microbiota structure in common carp.

Soils and agricultural products from the Red River basin in Northern Vietnam were reported to be contaminated by agrichemicals. To assess potential exposure of local farmers and consumers to these contaminants, pesticide use and management practices of local farmers were surveyed and residue concentrations were determined for recently used as well as for banned pesticides in water, soil, vegetables, and fish samples in two communes of Northern Vietnam. DDTs, HCHs, and Drin compounds still persist at relatively high concentrations in soil and occur in vegetable and fish samples. Recently used pesticides, such as fenobucarb, trichlorfon, cyfluthrin, and cypermethrin were detected in vegetable and fish samples. Thresholds for acceptable daily intake levels (ADI) were frequently reached in the analyzed food products pointing to the fact that current pesticide management practices do not only result in a pollution of the environment but also pose threats to human health.

Trichlorfon (TCF) is a broad-spectrum phosphorus (P)-containing pesticide, yet its effects on soil P fraction transformation and bacterial communities during the TCF degradation in soils is unknown. In this study, we investigated soil TCF degradation behavior at different contents of 50, 100 and 200 mg/kg, and analyzed residual TCF contents and metabolites by gas chromatography mass spectrometry after 216-h incubation. Our results suggested that TCF was gradually degraded in soils and was be initially hydrolyzed to dichlorvos via P–C bond cleavage and then other P-containing metabolites. By analyzing different P fractions and soil microbial community composition, we found significant increases of soil available phosphorus contents from 2.76 mg/kg (control) to 3.23 mg/kg (TCF-50), 5.12 mg/kg (TCF-100) and 5.72 mg/kg (TCF-200), respectively. Inorganic CaCl₂–P was easily and instantly transformed to primary mineral inorganic P (Pᵢ) forms of HCl–P and citrate-P, while the proportion of enzyme-P (a labile organic P) fluctuated throughout TCF degradation process. Soil available P contents and Pᵢ fractions were significantly correlated with the relative abundance of Actinobacteria. These results highlighted that Actinobacteria is the dominant soil species utilizing TCF as P sources to increase its community richness, and subsequently affect the transformation of P fractions to regulate soil P cycle. Our study gives new understanding on the microorganisms can involve soil P transformation during organophosphorus pesticides degradation in soils, highlighting the importance of bacteria in P transformation and pesticides soil decontamination.

Shrimps are the most widely and increasingly cultured crustaceans in land-based ponds in Taiwan. However, few studies have investigated the phthalate contamination of and insecticide residues in shrimp. In this study, we applied a validated method to analyze the phthalate and 18 insecticides residues in shrimp. A total of 46 samples of whiteleg, grass, or giant river shrimp were collected from aquafarms and production areas in Taiwan. We detected 0.02–0.70 mg/kg of di-2-ethylhexyl phthalate (DEHP) in three shrimps; 0.02–0.03 mg/kg of chlorpyrifos in three shrimps, and 0.03 mg/kg of trichlorfon in one shrimp, indicating that 6.52% and 8.70% of the samples contained phthalate and insecticide residues, respectively. Furthermore, the assessed risk was negligible and indicated no immediate health risk associated with shrimp consumption. Continual monitoring of the residues in shrimps is critical for further assessment of possible effects on human health.

Co-contamination with heavy metals and pesticides is a severe environmental problem, but little information is available regarding the simultaneous removal of these pollutants. In this study, we showed that Aspergillus sydowii strain PA F-2 isolated from soil contaminated with heavy metal and pesticides can simultaneously degrade trichlorfon (TCF) and adsorb Cd(II) from mineral salt medium. The maximum removal rates for TCF and Cd(II) were 55.52% and 57.90%, respectively, in the treatment containing 100 mg L⁻¹ TCF and 2 mg L⁻¹ Cd(II). As the initial Cd(II) concentration increased (2, 5, and 10 mg L⁻¹), the PA F-2 biomass, TCF degradation rate, and Cd(II) adsorption efficiency decreased, whereas the Cd(II) adsorption capacity by PA F-2 increased. The addition of exogenous glucose and sucrose significantly increased the PA F-2 biomass as well as the removal of TCF and Cd(II). Moreover, the TCF degradation pathway and Cd(II) adsorption mechanism were investigated by gas chromatography–mass spectrometry, scanning electron microscopy, and Fourier transform infrared spectroscopy. These results suggest that PA F-2 has potential applications in the bioremediation of TCF and Cd(II) co-contamination.

Farmland soil sprayed with organophosphorus pesticides (OPs) annually was investigated for the identification and characterization of OP-degrading microorganisms. Six bacterial strains were identified, including Brevundimonas faecalis MA-B12 and Alcaligenes faecalis subsp. parafaecalis MA-B13 for methamidophos degradation, Citrobacter freundii TF-B21 and Ochrobactrum intermedium TF-B23 for trichlorfon degradation, Ochrobactrum intermedium DV-B31 for dichlorvos degradation, and Bacillus cereus for dimethoate degradation. The optimal biodegradation conditions for OPs were obtained at pH 7.0 and incubation temperature ranging from 28 to 37 °C. In an 8-day batch test, biodegradation of the four OPs all followed first-order kinetics, with biodegradation rates ranging from 58.08 to 96.42%. Functional genes responsible for OPs degradation were obtained, including ophB, ampA, opdE, opd, opdA, and mpd. As these strains were indigenous strains isolated from farmland soils, they can be potentially used as bacterial consortium for the bioremediation of mixed OP-contaminated soils. A time-course genotoxicity assessment of the degradation products was done by a bacterial whole-cell bioreporter, revealing that biodegradation of trichlorfon, dichlorvos, and dimethoate resulted a decreased genotoxicity within 5 days, which, however, significantly increased on day 8. The result demonstrated that more toxic products may be produced during the biodegradation processes of OPs, and more attention should be put not only on the pesticides themselves, but also on the toxic effects of their degradation products. To the best of our knowledge, this is for the first time that the genotoxicity of OP degradation products was evaluated by the bioreporter assay, broadening our understanding on the genotoxic risks of OPs during biodegradation process. Graphical Abstract

The bacterial strain Sphingobium sp. YW16, which is capable of degrading monocrotophos, was isolated from paddy soil in China. Strain YW16 could hydrolyze monocrotophos to dimethylphosphate and N-methylacetoacetamide and utilize dimethylphosphate as the sole carbon source but could not utilize N-methylacetoacetamide. Strain YW16 also had the ability to hydrolyze other organophosphate pesticides. A fragment (7067 bp) that included the organophosphorus hydrolase gene, opdA, was acquired from strain YW16 using the shotgun technique combined with SEFA-PCR. Its sequence illustrated that opdA was included in TnopdA, which consisted of a transpose gene, a putative integrase gene, a putative ATP-binding protein gene, and opdA. Additionally, a conjugal transfer protein gene, traI, was located downstream of TnopdA. The juxtaposition of TnopdA with TraI suggests that opdA may be transferred from strain YW16 to other bacteria through conjugation. OpdA was able to hydrolyze a wide range of organophosphate pesticides, with the hydrolysis efficiency decreasing as follows: methyl parathion > fenitrothion > phoxim > dichlorvos > ethyl parathion > trichlorfon > triazophos > chlorpyrifos > monocrotophos > diazinon. This work provides the first report of opdA in the genus Sphingobium.