A 3D-Fluorescence Fingerprinting Approach to Detect Physiological Modifications Induced by Pesticide Poisoning in Apis mellifera: A Preliminary Study.

The combined use of 3D-fluorescence spectroscopy and independent component analysis using a differential fingerprinting approach has been applied with success to detect physiological effects of dimethoate in honeybees. Biochemical determinations combined with the identification of fluorescence zones that may correspond to proteins, NADH or neurotransmitters/neurohormones (octopamine, dopamine and serotonin) related to the physiological stress caused by the pesticide enabled phenomenological modeling of the physiological response in the honeybee using a simple and rapid method. The signals associated with the fluorophores involved in the response to stress were extracted from the fluorescence spectra using an unsupervised algorithm such as independent component analysis. The signals of different neurotransmitters were isolated on separated factorial components, thus facilitating their biochemical interpretation.

Synergistic toxicity of zno nanoparticles and dimethoate in mice: Enhancing their biodistribution by synergistic binding of serum albumin and dimethoate to zno nanoparticles.

The extensive applications of ZnO nanoparticles (nano ZnO) and dimethoate (DM) have increased the risk of humans' co-exposure to nano ZnO and DM. Here, we report the synergistic effect of nano ZnO and DM on their biodistribution and subacute toxicity in mice. Nano ZnO and DM had a synergistic toxicity in mice. In contrast, bulk ZnO and DM did not cause an obvious synergistic toxicity in mice. Although nano ZnO was low toxic to mice, coexposure to nano ZnO and DM significantly enhanced DM-induced oxidative damage in the liver. Coadministration of nano ZnO with DM significantly increased Zn accumulation by 30.9 ± 1.9% and DM accumulation by 45.6 ± 2.2% in the liver, respectively. The increased accumulations of DM and Zn in the liver reduced its cholinesterase activity from 5.65 ± 0.32 to 4.37 ± 0.49 U/mg protein and induced hepatic oxidative stress. Nano ZnO had 3-fold or 2.4-fold higher binding capability for serum albumin or DM, respectively, than bulk ZnO. In addition, serum albumin significantly increased the binding capability of nano ZnO for DM by approximately four times via the interaction of serum albumin and DM. The uptake of serum albumin- and DM-bound nano ZnO by the macrophages significantly increased DM accumulation in mice. Serum albumins play an important role in the synergistic toxicity of nano ZnO and DM. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1202-1212, 2017.

Combined in silico and in vivo studies shed insights into the acute acetylcholinesterase response in rat and human brain.

Combined in vivo and in silico studies were undertaken to gain insights into the change in mammalian brain acetylcholinesterase (AChE) activity under acute toxicity conditions in response to two representatives of organophosphates (OPs)--dichlorvos (DCV) and dimethoate (DM). In vivo experiments elucidated that DCV, at multiple sublethal doses for acute time periods, markedly reduced (10-25%) AChE activity, whereas with DM intoxication, a decrease in enzyme activity appeared to be lower, that is, (2-15%), in contrast to respective normal control (100%). Furthermore, a significant inhibition (P < 0.01) in the brain esterase activity was recorded for positive control animals treated with an alkylating agent-cyclophosphamide, with spontaneous reactivation at later time periods. In vivo results were further substantiated with in silico molecular docking analysis using "Autodock 4.2." The lowest binding energy obtained through the computational study strongly augment that DCV binds to brain AChE with greater affinity compared with DM with reference to ∆G and Ki values. Thus, the animal biochemical assay and computational assessment suggest that DM is better to be used over DCV. The precautionary antidote for exposed humans can be developed prior to dealing with OPs. The study will aid in efficacious and safe clinical use of the above-mentioned compounds.

Comparative evaluation of the efficiency of low-cost adsorbents and ligninolytic fungi to remove a combination of xenoestrogens and pesticides from a landfill leachate and abate its phytotoxicity.

In this study, two widely available low-cost adsorbents, almond shells and a green compost, and two ligninolytic fungi, Pleurotus ostreatus and Stereum hirsutum, were used to remove organic contaminants from a landfill leachate (LLe) and abate its phytotoxicity. The methodology adopted was based on the occurrence of two simultaneous processes, such as adsorption and bioremoval. The leachate was artificially contaminated with a mixture of the xenoestrogens bisphenol A (BPA), ethynilestadiol (EE2) and 4-n-nonylphenol (NP), the herbicide linuron and the insecticide dimethoate at concentrations of 10, 1, 1, 10 and 10 mg L(-1), respectively. Three adsorption substrates were prepared: potato dextrose agar alone or the same incorporating each adsorbent. The substrates were either not inoculated or inoculated with each fungus, separately, before to be superimposed on LLe. After 2 months, the residual amount of each contaminant, the electrical conductivity, the pH and the content of total phenols were measured in treated LLe. Germination assays using lettuce, ryegrass and radish were performed to evaluate LLe phytotoxicity. The combination substrate+P. ostreatus showed the best results with average removals of 88, 96, 99, 58 and 46% for BPA, EE2, NP, linuron and dimethoate, respectively. The same treatment considerably reduced the phenol content in LLe compared to no treatment. The combination substrate+S. hirsutum produced average removals of 39, 71, 100, 61 and 32% for BPA, EE2, NP, linuron and dimethoate, respectively. Also uninoculated substrates showed relevant adsorption capacities towards the five contaminants. Most treatments significantly reduced LLe phytotoxicity, especially on lettuce. The best results were obtained with the treatment compost+S. hirsutum, which produced root and shoot lengths and seedling biomass of lettuce, respectively, 2.3, 3.3, and 1.9 times those measured in untreated LLe. In general, germination results were negatively correlated with LLe properties like the residual amount of the contaminants, the electrical conductivity and the pH. These results show that the methodology adopted in the study, i.e., combined adsorption/biodegradation, is suitable not only to remove xenobiotic contaminants from the leachate but also to reduce considerably its inhibition on seed germination.

Anaerobic biodegradability of mixtures of pesticides in an expanded granular sludge bed reactor.

The biodegradability and toxicity of three commercial pesticides containing 2-methyl-4-chlorophenoxyacetic acid (MCPA), imidacloprid and dimethoate were evaluated individually, and a complex mixture of these pesticides was treated in an expanded granular sludge bed (EGSB) reactor. MCPA was partially biodegraded, while imidacloprid and dimethoate remained almost unaltered during the individual biodegradability tests. Cyclohexanone was identified as the major solvent in the dimethoate-bearing insecticide, which was completely removed regardless of the presence of other pesticides. The analysis of the inhibition over the acetoclastic methanogenesis showed IC(50) (half maximal inhibitory concentration) values of 474 and 367 mg/L for imidacloprid and dimethoate, respectively. The effect on the methanogenesis was negligible in the case of MCPA and cyclohexanone. Pesticides caused a dramatic decrease of the EGSB reactor performance. After 30 d acclimation, the EGSB reactor achieved a stable chemical oxygen demand (COD) removal efficiency and methane production of around 85% and 0.9 g CH(4)-COD/g COD, respectively, for MCPA, imidacloprid, dimethoate and cyclohexanone feed concentrations of 57, 20, 25 and 27 mg/L, respectively. The presence of complex pesticide mixtures led to synergistic/antagonistic responses, reducing the MCPA biodegradation and improving the removal of the insecticides' active ingredients, which were completely removed in the EGSB reactor.

Metabolomic analysis of the serum and urine of rats exposed to diazinon, dimethoate, and cypermethrin alone or in combination.

BACKGROUND: Multiple pesticides are often used in combination for plant protection and public health. Therefore, it is important to analyze the physiological changes induced by multiple pesticides exposure. The objective of this study was to investigate the combined toxicity of the widely-used organophosphorus and pyrethroid pesticides diazinon, dimethoate, and cypermethrin. METHODS: Male Wistar rats were administrated by gavage once daily with the three pesticides individual or in combination for consecutive 28 days. The metabolic components of serum and urine samples were detected by using 1H nuclear magnetic resonance (NMR)-based metabolomics method. Histopathological examination of liver and kidneys and serum biochemical determination were also carried out. RESULTS: The results showed that after the 28-day subacute exposure, serum glutamic transaminase and albumin were significantly increased and blood urea nitrogen was significantly decreased in the rats exposed to the mixture of the pesticides compared with the control rats, suggesting that the co-exposure impaired liver and kidney function. Metabolomics analysis indicated that the indicators 14 metabolites were statistically significant altered in the rats after the exposure of the pesticides. The increase in 3-hydroxybutyric acid in urine or decrease of lactate and N-acetyl-L-cysteine in serum could be a potentially sensitive biomarker of the subchronic combined effects of the three insecticides. The reduction level of 2-oxoglutarate and creatinine in urine may be indicative of dysfunction of liver and kidneys. CONCLUSION: In summary, the exposure of rats to pesticides diazinon, dimethoate, and cypermethrin could cause disorder of lipid and amino acid metabolism, induction of oxidative stress, and dysfunction of liver and kidneys, which contributes to the understanding of combined toxic effects of the pesticides revealed by using the metabolomics analysis of the urine and serum profiles.

Integrated transcriptomic and metabolomic analyses reveal the toxic effects of dimethoate on green vegetable soya bean seedlings.

The insecticide dimethoate, an organophosphate, has been used on crops, soybeans, fruits, and vegetables since the 1960s and is considered one of the most widely used pesticides. However, the understanding of the molecular mechanisms of dimethoate in crops, especially crop seedlings, is still limited. The green vegetable soya bean (Glycine max merr) is usually used as a vegetable-like fruit of soybean in many Asian countries. This study aimed to analyze the effect of dimethoate on the growth of green vegetable soya bean seedlings at the metabolic and transcriptional levels. An integrated analysis of the transcriptome and metabolome was performed to determine the responses of green vegetable soya bean seedlings to different concentrations (D1 for low dose, D2 for high dose and C for control) of dimethoate. In omics analyses, 4156 differentially expressed genes (DEGs) and 1935 differentially abundant metabolites (DAMs) were identified in the D1/C comparison, and 11,162 DEGs and 819 DAMs were identified in D2/C. Correlation analyses revealed dimethoate affected the metabolic pathways of green vegetable soya beans such as the biosynthesis of secondary metabolites and microbial metabolism in diverse environmental pathways, demonstrating that even small doses of dimethoate can affect green vegetable soya bean seedlings in a short period of time. Our study further enriches our understanding of the molecular mechanisms by which green vegetable soya beans are treated with dimethoate and provides a deeper understanding of the effects of dimethoate on crops.

Chlorophyll fluorescence in sentinel plants for the surveillance of chemical risk.

This research aimed to develop natural plant systems to serve as biological sentinels for the detection of organophosphate pesticides in the environment. The working hypothesis was that the presence of the pesticide in the environment caused changes in the content of pigments and in the photosynthetic functioning of the plant, which could be evaluated non-destructively through the analysis of reflected light and emitted fluorescence. The objective of the research was to furnish in vivo indicators derived from spectroscopic parameters, serving as early alert signals for the presence of organophosphates in the environment. In this context, the effects of two pesticides, Chlorpyrifos and Dimethoate, on the spectroscopic properties of aquatic plants (Vallisneria nana and Spathyfillum wallisii) were studied. Chlorophyll-a variable fluorescence allowed monitoring both pesticides' presence before any damage was observed at the naked eye, with the analysis of the fast transient (OJIP curve) proving more responsive than Kautsky kinetics, steady-state fluorescence, or reflectance measurements. Pesticides produced a decrease in the maximum quantum yield of PSII photochemistry, in the proportion of PSII photochemical deexcitation relative to PSII non photochemical decay and in the probability that trapped excitons moved electrons into the photosynthetic transport chain beyond QA-. Additionally, an increase in the proportion of absorbed energy being dissipated as heat rather than being utilized in the photosynthetic process, was notorious. The pesticides induced a higher deactivation of chlorophyll excited states by photophysical pathways (including fluorescence) with a decrease in the quantum yields of photosystem II and heat dissipation by non-photochemical quenching. The investigated aquatic plants served as sentinels for the presence of pesticides in the environment, with the alert signal starting within the first milliseconds of electronic transport in the photosynthetic chain. Organophosphates damage animals' central nervous systems similarly to certain compounds found in chemical weapons, thus raising the possibility that sentinel plants could potentially signal the presence of such weapons.

Biodegradation of the organophosphate dimethoate by Lactobacillus plantarum during milk fermentation.

Bioremediation of pesticides in contaminated foodstuffs using probiotics has attracted great attention in recent years, but some intermediate products may have profound effects on the toxicity of treated food. Therefore, this work studied the degradation mechanism of dimethoate in milk by L. plantarum, and analyzed the toxicity of degradation products. The results showed that under the optimal conditions, L. plantarum can degrade 81.28% of dimethoate. Dimethoate had high binding affinities to phosphatase with the free energy of -16.67 kcal/mol, and amino acid residues, Gln375 and SER415 played important roles in the catalysis process. Five degradation products were identified using UPLC-QTOF/MS, and their toxicity was estimated using quantitative structure-activity relationship models. Some intermediate products were predicted to be toxic, which should not be ignored, but the overall toxicity of milk decreased after fermentation. Furthermore, the pH and titratable acidity of the fermented milk were 4.25 and 85 ◦T, respectively.

Methamidophos, dichlorvos, O-methoate and diazinon pesticides used in Turkey make a covalent bond with butyrylcholinesterase detected by mass spectrometry.

Organophosphorus pesticides used most commonly in Turkey include methamidophos, dichlorvos, O-methoate and diazinon. These toxic chemicals or their metabolites make a covalent bond with the active site serine of butyrylcholinesterase. Our goal was to identify the adducts that result from the reaction of human butyrylcholinesterase with these pesticides. Highly purified human butyrylcholinesterase was treated with a 20-fold molar excess of pesticide. The protein was denatured by boiling and digested with trypsin. MS and MSMS spectra of HPLC-purified peptides were acquired on a MALDI-TOF-TOF 4800 mass spectrometer. It was found that methamidophos added a mass of +93, consistent with addition of methoxy aminophosphate. A minor amount of adduct with an added mass of +109 was also found. Dichlorvos and O-methoate both made dimethoxyphosphate (+108) and monomethoxyphosphate adducts (+94). Diazinon gave a novel adduct with an added mass of +152 consistent with diethoxythiophosphate. Inhibition of enzyme activity in the presence of diazinon developed slowly (15 h), concomitant with isomerization of diazinon via a thiono-thiolo rearrangement. The isomer of diazinon yielded diethoxyphosphate and monoethoxyphosphate adducts with added masses of +136 and +108. MSMS spectra confirmed that each of the pesticides studied made a covalent bond with serine 198 of butyrylcholinesterase. These results can be used to identify the class of pesticides to which a patient was exposed.

Cherry laurel fruit extract counters dimethoate-induced reproductive impairment and testicular apoptosis.

Dimethoate is an organophosphorus pesticide used against agricultural insects, which causes oxidative stress and damage in many organs, including the reproductive ones. Cherry laurel (Laurocerasus officinalis Roem.) fruit is rich in vitamins and phenolic compounds with antioxidant effect. The aim of this study was to investigate how effective its extract would be against dimethoate-induced testis and sperm damage in rats. Sixty animals were divided in six groups of 10. Group 1 (control) received only 1 mL of saline (0.9 % NaCl). Group 2 received 7 mg/kg of dimethoate in 1 mL of saline. Group 3 received 4 mg/kg of extract in 1 mL of saline. Group 4 received the extract 30 min before dimethoate administration. Group 5 received vitamin C (positive control, 100 mg/kg in 1 mL of saline) 30 min before dimethoate administration. Group 6 received only dimethoate for the first four weeks and then a combination of dimethoate and extract for another four weeks. All doses were administered daily by oral gavage. After eight weeks of treatment, the rats were euthanised and their reproductive organs removed. We took their body and reproductive organ weights and evaluated testicular oxidative stress, semen characteristics, sperm DNA damage, testicular apoptosis, and histopathological changes. Dimethoate significantly decreased body and reproductive organ weights, sperm motility and concentration, testicular superoxide dismutase, and glutathione-peroxidase activities and significantly increased lipid peroxidation, abnormal sperm rate, sperm DNA damage, testicular apoptosis, and caused histopathological lesions. Cherry laurel extract significantly countered many dimethoate-induced adverse effects, both as pre- and post-treatment, including reproductive organ weight, semen parameters, oxidant-antioxidant balance, sperm DNA integrity, testicular apoptosis, and histological structure. Our findings clearly suggest that the beneficial effects of the extract are associated with countering oxidative stress, lipid peroxidation in particular.

Co-metabolic degradation of dimethoate by Raoultella sp. X1.

A bacterium Raoultella sp. X1, based on its 16S rRNA gene sequence, was isolated. Characteristics regarding the bacterial morphology, physiology, and genetics were investigated with an electron microscopy and conventional microbiological techniques. Although the isolate grew and degraded dimethoate poorly when the chemical was used as a sole carbon and energy source, it was able to remove up to 75% of dimethoate via co-metabolism. With a response surface methodology, we optimized carbon, nitrogen and phosphorus concentrations of the media for dimethoate degradation. Raoultella sp. X1 has a potential to be a useful organism for dimethoate degradation and a model strain for studying this biological process at the molecular level.

Impact assessment of pesticide residues in fish of Ganga river around Kolkata in West Bengal.

An investigation was conducted from 2001 to 2005 for determining the residual concentration of five pesticides, viz., total-HCH, total-DDT, total-Endosulfan, Dimethoate and Malathion in fish samples collected from various points of the river Ganga. Fish samples were analyzed for pesticide residues using standard laboratory procedures by GC method. It was found that total-HCH concentration remains above the MRL values for maximum number of times in comparison to four other pesticides. The pesticide contamination to fish may be due to indiscriminate discharge of polluted and untreated sewage-sludge to the river. The pesticide contents in some places are alarming. Thus proper care, maintenance, treatment and disposal of sewage water and sludge are most vital and should be the prime thrust for the nation.

Influence of Bi 58 Nowy (38% dimethoate) on pyrantel embonate concentration in the liver of rats.

The aim of the study was to determine the concentration of pyrantel residues in the liver of rats in different time points after oral administration of pyrantel embonate as well as combined administration of the Bi 58 Nowy preparation (38% of dimethoate) and pyrantel embonate. The experiment was conducted in two stages involving different doses of compounds and modes of exposure. At the first stage, the animals were administered pyrantel embonate with a stomach tube at a dose of 1000 mg/kg b.w. twice in a two-week interval, i.e. on day 14 and 28, and the Bi 58 Nowy preparation with drinking water at a dose of 15.48 mg/kg b.w. for 28 days. At the second stage, the rats received pyrantel embonate at a dose of 400 mg/kg b.w. with a stomach tube for 3 consecutive days, whereas the Bi 58 Nowy preparation was administered at a dose of 38.7 mg/kg b.w. also with a stomach tube for 5 consecutive days. In the rats doubly administered with pyrantel embonate, its residues were present until day 14, whereas when the drug was administered for 3 consecutive days they were present until day 7 of the experiment. The maximum concentration of pyrantel embonate was found in the liver after the 3rd hour, whereas a considerable decrease occurred between the 3rd and the 12th hour. The combined administration of pyrantel embonate and the Bi 58 Nowy preparation caused a significant decrease in the concentration of pyrantel residues in the liver 3 and 6 hours after exposure, as compared to the rats receiving the drug alone.

Identification and Dissipation of Omethoate and Its Main Metabolite DMP in Wheat Determined by UPLC-QTOF/MS.

A study was carried out to evaluate the dissipation kinetics of field-applied omethoate during wheat storage. Both the identification and metabolic dynamics of omethoate metabolites were analyzed using UPLC-QTOF/MS. The presence of the metabolite dimethyl phosphate (DMP) was confirmed in wheat samples with applied omethoate. This might be because the group attached to the P atom of omethoate is replaced by a hydroxyl group through hydrolysis, thus leading to the formation of the specific metabolite DMP during wheat storage. Although the initial concentrations of DMP in different doses were considerably lower than those of omethoate, the half-life values of DMP were 11.87-31.50 days, which were close to the half-life of the parent omethoate (11.85-30.94 days). This indicates that potential health risks might be caused by dietary exposure to DMP and omethoate. Therefore, more importance should be given to the risk assessment for omethoate and its metabolite DMP in wheat.

Assessment of the dissipation, pre-harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites in greenhouse cucumber (Cucumis sativus L.).

BACKGROUND: The dissipation behavior, pre-harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites were investigated in greenhouse cucumber in Tianjin, northern China, to ensure raw consumption safety. RESULTS: Carbosulfan was metabolized to carbofuran, dibutylamine, 3-hydroxycarbofuran and 3-ketocarbofuran, and dimethoate was degraded to omethoate in cucumber fruits and leaves. The dissipation of carbosulfan, carbofuran, 3-hydroxycarbofuran and dimethoate fitted first-order kinetics well, with R2 ranging from 0.912 to 0.992, and their half-lives were 2.6, 2.7, 2.4 and 5.2 days in cucumber fruits and 2.8, 3.0, 4.6 and 2.5 days in leaves, respectively. The estimated daily intakes of the active ingredients and their relevant metabolites were 0.1-4% of the corresponding acceptable daily intakes. Acute oral exposure to carbofuran (a metabolite of carbosulfan) represented 367% of the acute reference dose (ARfD) for 1-6-year-old Chinese children and 227% for the general Chinese population. CONCLUSION: A minimum pre-harvest interval of 12 days for carbosulfan is proposed to ensure safe consumption of cucumber. The slow dissipation rate of omethoate in cucumber reveals that a longer pre-harvest interval (≥ 27 days) is necessary to prevent dietary risk when dimethoate is applied to cucumber. © 2018 Society of Chemical Industry.

Oxidation of two organophosphorous insecticides by the photo-assisted Fenton reaction.

The photocatalytic degradation of two selected insecticides (dimethoate and methyl parathion) has been studied using the photo-assisted Fenton reaction. The degradation kinetics were studied under different conditions such as iron's and oxidant's concentration, temperature and inorganic ions. The degradation rates proved to be strongly influenced by these parameters. The replacement of hydrogen peroxide with peroxydisulfate was also tested in a photo-Fenton-like reaction. This system achieved high degradation rates of the selected compounds. Intermediate products formed during photocatalytic treatment were identified by means of solid-phase extraction (SPE) coupled to gas chromatography-mass spectroscopy techniques (GC-MS). Eight possible by-products were identified for parathion methyl and three for dimethoate formed through mainly oxidation and dealkylation reactions. Mineralization studies showed also that the photo-Fenton and the photo-Fenton-like systems are able to achieve mineralization of the insecticides. However, complete detoxification is achieved only in the presence of the photo-Fenton reagent.

Detoxification and/or increase of the biodegradability of aqueous solutions of dimethoate by means of solar photocatalysis.

Different methods have been used to measure changes in biodegradability/toxicity of aqueous solutions of the pesticide Laition (a commercial formula of methidathion) when it is treated by means of TiO(2) photocatalysis: short time biological oxygen demand (BOD(st)) was used to determine the instantaneous biodegradability of the sample; BOD(5) was also chosen to determine biodegradability, employing in this case the manometric method; the BOD(5)/COD ratio was also calculated. Finally, the Zahn-Wellens test was employed to evaluate the long-term biodegradation of the effluents. The inhibition of the respiration of activated sludge in the presence of toxic pollutants was used to test the toxicity of the treated sample. An alternative method based on the decrease of BOD(5) of a very biodegradable mixture (glucose+glutamic acid) upon addition of the toxic solution was also employed. Similar trends were obtained with all methods and allowed us to distinguish between two periods: At the beginning of the reaction, there is a decrease in the concentration of dimethoate to reach complete abatement of this pesticide; this produces a nearly complete detoxification of the solution and a very significant increase of biodegradability (BOD(5)/COD ratio reached values close to 0.5 and important increase of BOD(5) and BOD(st) were observed). Beyond this point, slow mineralization is detected, but further improvement of the biodegradability cannot be achieved.

Study of the removal of dichlorvos and dimethoate in a titanium dioxide mediated photocatalytic process through the examination of intermediates and the reaction mechanism.

The photocatalytic oxidation of two selected organophosphorous insecticides (dichlorvos and dimethoate) has been investigated. The aim of the study was the identification of the intermediates that are formed during photocatalytic treatment. Intermediate products from the slurry system were identified by means of solid-phase extraction (SPE) coupled to gas chromatography-mass spectroscopy techniques (GC-MS). Nine possible by-products were identified for dimethoate and three for dichlorvos. A proposed degradation pathway for each insecticide is presented, involving mainly oxidation and dealkylation reactions. The results demonstrated that some of the transient intermediates formed (oxon derivatives, disulfide, chlorinated fragments), were more toxic compared to parent compounds whereas most of them are less toxic than the parent compounds.

Biodegradation of Chlorpyrifos, Malathion, and Dimethoate by Three Strains of Bacteria Isolated from Pesticide-Polluted Soils in Sudan.

This study was done to identify pesticide-biodegrading microorganisms and to characterize degradation rates. Bacillus safensis strain FO-36bT, Bacillus subtilis subsp. inaquosorum strain KCTC13429T, and Bacillus cereus strain ATCC14579T were isolated from pesticide-polluted soil in Sudan, separately incubated with each pesticide with periodic samples drawn for GC and GC-MS. Pesticide biodegradation followed a biphasic model. α and ß half-lives (days) of chlorpyrifos, malathion, and dimethoate in B. safensis culture were 2.13, 4.76; 2.59, 5.66; and 9.5, 11.0, respectively. Values in B. subtilis and B. cereus cultures were 4.09, 9.45 and 4.33, 9.99 for chlorpyrifos; 2.99, 5.36 and 2.43, 4.71 for malathion; and 9.53, 15.11 and 4.16, 9.27 for dimethoate. No metabolite was detected in B. subtilis cultures, whereas a few were detected from B. safensis and B. cereus cultures. Bacterial efficiency can be ordered as B. safensis > B. subtilis > B. cereus for chlorpyrifos and B. cereus > B. subtilis > B. safensis for malathion and dimethoate.