Malathion Monocarboxylic Acid Research Articles

Biodegradation of Malathion in Amended Soil by Indigenous Novel Bacterial Consortia and Analysis of Degradation Pathway

The capabilities of pure bacterial strains and their consortia isolated from agricultural soil were evaluated during a bioremediation process of the organophosphate pesticide malathion. The pure bacterial strains efficiently degraded 50.16–68.47% of the pesticide within 15 days of incubation, and metabolites were observed to accumulate in the soil. The consortia of three bacterial species [Micrococcus aloeverae (MAGK3) + Bacillus cereus (AGB3) + Bacillus paramycoides (AGM5)] degraded the malathion more effectively, and complete malathion removal was observed by the 15th day in soils inoculated with that consortium. In contrast, the combined activity of any two of these strains was lower than the mixed consortium of all of the strains. Individual mixed consortia of Micrococcus aloeverae (MAGK3) + Bacillus cereus (AGB3); Micrococcus aloeverae (MAGK3) + Bacillus paramycoides (AGM5); and Bacillus cereus (AGB3) + Bacillus paramycoides (AGM5) caused 76.58%, 70.95%, and 88.61% malathion degradation in soil, respectively. Several intermediate metabolites like malaoxon, malathion monocarboxylic acid, diethyl fumarate, and trimethyl thiophosphate were found to accumulate and be successively degraded during the bioremediation process via GC–MS detection. Thus, inoculating with a highly potent bacterial consortium isolated from in situ soil may result in the most effective pesticide degradation to significantly relieve soils from pesticide residues, and could be considered a prospective approach for the degradation and detoxification of environments contaminated with malathion and other organophosphate pesticides. This study reports the use of a mixed culture of Indigenous bacterial species for successful malathion degradation.

Isolation and Identification of Efficient Malathion-Degrading Bacteria from Deep-Sea Hydrothermal Sediment.

The genetic and metabolic diversity of deep-sea microorganisms play important roles in phosphorus and sulfur cycles in the ocean, distinguishing them from terrestrial counterparts. Malathion is a representative organophosphorus component in herbicides, pesticides, and insecticides and is analogues of neurotoxic agent. Malathion has been one of the best-selling generic organophosphate insecticides from 1980 to 2012. Most of the sprayed malathion has migrated by surface runoff to ocean sinks, and it is highly toxic to aquatic organisms. Hitherto, there is no report on bacterial cultures capable of degrading malathion isolated from deep-sea sediment. In this study, eight bacterial strains, isolated from sediments from deep-sea hydrothermal regions, were identified as malathion degradators. Two of the tested strains, Pseudidiomarina homiensis strain FG2 and Pseudidiomarina sp. strain CB1, can completely degrade an initial concentration of 500 mg/L malathion within 36 h. Since the two strains have abundant carboxylesterases (CEs) genes, malathion monocarboxylic acid (MMC α and MMC β) and dibasic carboxylic acid were detected as key intermediate metabolites of malathion degradation, and the pathway of malathion degradation between the two strains was identified as a passage from malathion monocarboxylic acid to malathion dicarboxylic acid.

New approach for biodegradation of Malathion pesticide by Bacillus sp. isolated from agricultural field: Bioreactor and kinetics

This study is focuses on understanding bioremediation strategies for biodegrdadation of Malathion by isolating potential microbes, enhancing rate in batch packed bed bioreactor, confirming metabolites, and then proteomics. The bacterial species were isolated and identified from agricultural fields. Biodegradation of Malathion was studied by isolated species, and it was observed that Bacillus sp. S4 is more effective than Bacillus sp. S1 and Bacillus sp. S2 for Malathion bioremediation. The maximum removal efficiency of Malathion (72%) was achieved at 200 mg/L in a free cell and it was further improved to 84% in batch packed bed bioreactor at optimum pH (7.5) and temperature (32 °C). The leachate was analyzed, and two metabolites, namely, Malathion monocarboxylic acid and Succinic acid, were identified. In Monod growth kinetics, the maximum specific growth rate (0.254 per day), rate constant (119.5 mg/day) and in Andrew-Haldane inhibition kinetics, the maximum specific growth rate (0.228/day), rate constant (114.8 mg/L), and inhibition constant (348.43 mg/L) were evaluated. Identified proteins were characterized by sequential, functional, and structural analysis. The best quality hypothetical protein (NP_390682.1) from treated Malathion was used for docking calculation. The residues of major active binding sites ILE151, GLY152, ASN155, SER156, SER157, VAL159, HIS160, PRO161, GLU192, GLU195, VAL196, and ARG199 involved in interaction with binding energy 4.318 kcal/mol and dissociation constant 683697536.0 PM, were investigated. The results obtained are expected to be helpful in the practical application of Bacillus sp. S4 for the removal of Malathion from the contaminated environment under in situ conditions.

Isolation and characterization of two malathiondegrading Pseudomonas sp. in Egypt

Pseudomonas aeruginosa and Pseudomonas mendocina degrading malathion were studied. Morphological, biochemical and 16S rRNA genes for bacterial identification were selected. Biodegradation of some organophosphorus compounds with the 2 bacterial isolates was determined by high performance liquid chromatography (HPLC). P. aeruginosa strain completely removed diazinon, malathion and fenitrothion, but not chlorpyrifos within 14 days. P. mendocina strain was not able to degrade malathion, diazinon and chlorpyrifos completely and no significant degradation for chlorpyrifos. The bacterial growth curve showed a steady increase in the two bacterial isolates masses during malathion degradation. The highest growth rates were with yeast extract, glucose and citrate for the 2 isolates, but not with phenol. Shaked high inoculum density with incubation at 30°C of malathion bacterial cultures were found to be the optimum conditions for malathion degradation. Bacterial culture extracts subjected to liquid chromatography/mass spectrometry (LC/MS) analysis revealed that the separated products were malathion monocarboxylic acid and malathion dicarboxylic acid. Molecular characterization of carboxylesterase enzyme revealed that carboxylesterase amino acid sequences of the 2 isolates showed high identity to other carboxylesterase enzymes of P. aeruginosa and P. mendocina , respectively. Phylogenetic analysis showed that P. aeruginosa was localized in a separate branch from other carboxylesterase producing Pseudomonas sp. So, it is suggested that this enzyme is a novel esterase enzyme. Use of pesticide-degrading microbial systems for removal of organophosphorus compounds from the contaminated sites requires an understanding of ecological requirements of degrading strains. The results provided an important insight into determining the bioremediation potential of both strains. But the mentioned bacteria cannot be the aim of bioremediation due to risk of public health hazard, hence these bacteria cannot be used in bioremediation but their purified enzymes could. Key words : Biodegradation, carboxylestrase, organopgosphorus pesticides, Pseudomonas aeruginosa, Pseudomonas mendocina.

English

Pseudomonas aeruginosa and Pseudomonas mendocina degrading malathion were studied. Morphological, biochemical and 16S rRNA genes for bacterial identification were selected. Biodegradation of some organophosphorus compounds with the 2 bacterial isolates was determined by high performance liquid chromatography (HPLC). P. aeruginosa strain completely removed diazinon, malathion and fenitrothion, but not chlorpyrifos within 14 days. P. mendocina strain was not able to degrade malathion, diazinon and chlorpyrifos completely and no significant degradation for chlorpyrifos. The bacterial growth curve showed a steady increase in the two bacterial isolates masses during malathion degradation. The highest growth rates were with yeast extract, glucose and citrate for the 2 isolates, but not with phenol. Shaked high inoculum density with incubation at 30°C of malathion bacterial cultures were found to be the optimum conditions for malathion degradation. Bacterial culture extracts subjected to liquid chromatography/mass spectrometry (LC/MS) analysis revealed that the separated products were malathion monocarboxylic acid and malathion dicarboxylic acid. Molecular characterization of carboxylesterase enzyme revealed that carboxylesterase amino acid sequences of the 2 isolates showed high identity to other carboxylesterase enzymes of P. aeruginosa and P. mendocina, respectively. Phylogenetic analysis showed that P. aeruginosa was localized in a separate branch from other carboxylesterase producing Pseudomonas sp. So, it is suggested that this enzyme is a novel esterase enzyme. Use of pesticide-degrading microbial systems for removal of organophosphorus compounds from the contaminated sites requires an understanding of ecological requirements of degrading strains. The results provided an important insight into determining the bioremediation potential of both strains. But the mentioned bacteria cannot be the aim of bioremediation due to risk of public health hazard, hence these bacteria cannot be used in bioremediation but their purified enzymes could.   Key words: Biodegradation, carboxylestrase, organopgosphorus pesticides, Pseudomonas aeruginosa, Pseudomonas mendocina.

Comparison of solid phase- and liquid/liquid-extraction for the purification of hair extract prior to multi-class pesticides analysis

The present study focuses on the influence of a purification step - after extraction of pesticides from hair and before analysis of the extract - on the sensitivity of analytical methods including compounds from different chemical classes (both parent and metabolites). Sixty-seven pesticides and metabolites from different chemical classes were tested here: organochlorines, organophosphates, carbamates, pyrethroids, ureas, azoles, phenylpyrazoles and neonicotinoids. Two gas chromatography-negative chemical ionization-tandem mass spectrometry methods and one based on ultra-performance liquid chromatography-electrospray tandem mass spectrometry were used. Seven solid-phase extraction cartridges: C18, S-DVB, PS-DVB, GCB, GCB/PSA, SAX/PSA and Florisil/PSA were tested and compared to more classical liquid-liquid extraction procedures using ethyl acetate, hexane and dichloromethane. Although LLE allowed obtaining good results for some compounds, on the whole, SPE clearly provided better recovery for the majority of the pesticide residues tested in the present study. GCB/PSA was clearly the best suited to non-polar compounds such as organochlorines, pyrethroids and organophosphates, with recovery ranging from 45.9% (diflufenican) to 117.1% (parathion methyl). For hydrophilic metabolites (e.g. dialkyl phosphates and other organophosphate metabolites, pyrethroid metabolites, phenols and carbamate metabolites), the best results were obtained with PS-DVB, with recovery ranged from 10.3% (malathion monocarboxylic acid) to 93.1% (para-nitrophenol). For hydrophilic parent pesticides (e.g. neonicotinoids, carbamates, azoles) and metabolites without nucleophilic functions, the best recovery was obtained with SAX/PSA, with recovery ranging from 52.1% (3-hydroxycarbofuran) to 100.9% (3,4-dichloroaniline). Solid phase extraction was found to be more suitable than the liquid-liquid extraction for pesticides and their metabolites determination in terms of number of extracted compounds and their recovery. Moreover, the use of solid phase extraction cartridges has enabled the reduction of the analytical background noise, resulting in better chromatographic separations.

Identification of Carboxylesterase Metabolites of Residual Malathion in Wheat Kernels Using Semi-Micro Radio Liquid Chromatography

Since residual malathion in wheat kernels is shown to be enzymatically decomposed during sample preparation using the Japanese official method for pesticide analysis, the decomposition products were identified by semi-micro radio liquid chromatography (LC). The reaction mixture of the supernatant of wheat kernel homogenate incubated with [ 14 C] malathion for 0–8 hr was fractionated, and the radioactive decomposition products in the fractions were identified by comparison with the retention time of fifteen reference standards. Twelve of these products occurring in the environment, diethyl fumarate, diethyl maleate, diethyl malate and diethyl succinate, and their hydrolysate and desmethyl malathion dicarboxylic acid were not detected in the reaction mixture, indicating no contribution of organophosphorus hydrolase or methyl transferase. A trace amount of desmethyl malathion was observed, however, this seemed to be non-enzymatically produced. Malathion monocarboxylic acid and malathion dicarboxylic acid were identified as the major products by the LC condition with and without an ion pair reagent, respectively. The half life of malathion decomposition was 2.1 hr, and the reaction time course of these products demonstrated that malathion was decomposed to malathion monocarboxylic acid followe db y malathion dicarboxylic acid. These results suggested that residual malathion in wheat kernels was mainly hydrolyzed to malathion carboxylic acids by wheat carboxylesterase during the sample preparation.

Maternal hair—An appropriate matrix for detecting maternal exposure to pesticides during pregnancy

The detection of exposure of pregnant women to toxicants in the environment is important because these compounds can be harmful to the health of the woman and her fetus. The aim of this study was to analyze for pesticides/herbicides in paired maternal hair and blood samples to determine the most appropriate matrix for detecting maternal exposure to these compounds. A total of 449 pregnant women were prospectively recruited at midgestation from an agricultural site in the Philippines where a preliminary survey indicated significant use at home and on the farm of the following compounds: propoxur, cyfluthrin, chlorpyrifos, cypermethrin, pretilachlor, bioallethrin, malathion, diazinon, and transfluthrin. Paired maternal hair and blood samples were obtained from each subject upon recruitment into the study (midgestation) and at birth and were analyzed for the above compounds, as well as lindane and DDT [1,1,1-trichloro-2-2-bis( p-chlorophenyl) ethane], and some of their known metabolites by gas chromatography/mass spectrometry. The highest exposure rate was seen for propoxur and bioallethrin and maternal hair analysis provided the highest detection rate for these two compounds, compared to blood, at both time periods: (1) At midgestation, 10.5% positive for propoxur in hair compared to 0.7% in blood ( P < 0.001 ) and for bioallethrin, 11.9% positive in hair compared to 0% in blood ( P ⩽ 0.001 ), and (2) at birth, 11.8% positive for propoxur in hair compared to 4% in blood ( P ⩽ 0.001 ) and for bioallethrin, 7.8% in hair compared to 0% in blood ( P ⩽ 0.001 ). A small number of maternal hair samples were also positive for malathion, chlorpyrifos, pretilachlor, and DDT. Only a few of the pesticide metabolites were detected, principally 3-phenoxybenzoic acid, malathion monocarboxylic acid, and DDE [1,1,dichloro-2-2-bis( p-chlorophenyl)ethylene], and they were mostly found in maternal blood. There was a significant association between the use of the home spray pesticide, Baygon, and propoxur in maternal hair at birth ( P = 0.001 ) and between the use of a slow-burning mosquito coil and the presence of bioallethrin in maternal hair at midgestation and at birth ( P = 0.001 , P ⩽ 0.041 , respectively). There is significant exposure of the pregnant woman to pesticides, particularly to pesticides that are used at home. Our study demonstrates the advantages of analyzing maternal hair as a readily available biologic matrix for studying maternal exposure to toxicants in the environment, compared to blood. For propoxur, there was a 3- to 15-fold higher detection rate of the pesticide in maternal hair as compared to blood. As for the other pesticides, bioallethrin, malathion, chlorpyrifos, and DDT were exclusively found in maternal hair compared to blood. On the other hand, pesticide metabolites were infrequently found in maternal hair or maternal blood. Pesticides in blood most likely represent acute exposure, whereas pesticides in hair represent past and/or concurrent exposure. The high sensitivity, wide window of exposure, availability, and ease of hair collection are distinct advantages in using hair to detect exposure to pesticides among pregnant women. However, pesticides in maternal hair may also be secondary to passive exposure and therefore not truly representative of the internal pesticide dose. Finally, the analysis of maternal hair for pesticides as an index of maternal exposure to pesticides in the environment allows the institution of measures to prevent further exposure during pregnancy.

Specificity of the fluorescein transport process in Malpighian tubules of the cricketAcheta domesticus

We demonstrate the presence of an efficient, multispecific transport system for excretion of organic anions in the Malpighian tubules of the cricket Acheta domesticus using fluorescein (FL) as a model substrate. Malpighian tubules rapidly accumulated FL via a high affinity process (Km = 7.75 micromol l(-1)); uptake was completely eliminated by the prototypical organic anion transport inhibitor probenecid (1 mmol l(-1)), but not by p-aminohippuric acid (3 mmol l(-1)). FL uptake was inhibited by monocarboxylic acids at a high concentration (3 mmol l(-1)), and inhibition was more effective with an increase in the carbon chain of the monocarboxylic acid (37% inhibition by 5-carbon valeric acid, and 89% inhibition by 7-carbon caprylic acid). Likewise, tests using a series of aliphatic glutathione conjugates indicated that only the compound with the longest side-chain (decyl-glutathione) significantly inhibited FL uptake (81% inhibition). FL uptake was inhibited by a number of xenobiotics, including a plant alkaloid (quinine), herbicides (2,4-dichlorophenoxyacetic acid and 4-(2,4-dichlorophenoxy)-butyric acid), and the insecticide metabolites malathion monocarboxylic acid (MMA) and 3-phenoxybenzoic acid (PBA), suggesting that this transport system plays an active role in excretion of xenobiotics from Acheta by Malpighian tubules. HPLC quantification of MMA and PBA accumulation into Malpighian tubules verified that MMA accumulation was via a mediated transport process, but suggested that PBA accumulation was by nonspecific binding. The presence of a transport system in Malpighian tubules that handles at least one pesticide metabolite (MMA) suggests that transport processes could be a mechanism conferring resistance to xenobiotic exposure in insects.

Monitoring of pesticide applicators for potential dermal exposure to malathion and biomarkers in urine

Malathion was applied to roses in three Finnish greenhouses by hand held lance sprayers. The potential dermal exposure of applicators to this insecticide was measured. Total urine production of each applicator was also collected up to 24 h post application. In the urine samples the specific metabolite of malathion, malathion monocarboxylic acid (MMA), and the creatinine content were determined. The potential dermal exposure results show that during the application of malathion, the applicators’ lower limbs accounted, on average, for 48%, while the upper limbs accounted for 19% of the potential dermal exposure. Moreover, hands and chest and back and head regions accounted for 30 and 3%, respectively. Based on the urine measurements, it was observed that the excretion of MMA was very rapid reaching a maximum at about 6–7 h after the completion of the application. In the urine samples collected, MMA was found to be present in relatively small amounts.

Bioavailability to rats and toxicological potential in mice of bound residues of malathion in beans.

Under conditions of local practice, the application of 2,3-succinate-14C-malathion on beans led to the formation of 17-18% of bound 14C-residues after 30 weeks. When fed to rats, 75% of these residues became bioavailable after 2 days with the major part, excreted via expired air (8%) and urine (60%). The main radioactive metabolites detected in urine were malathion monocarboxylic acid and malathion dicarboxylic acid. Feeding of bound residues to mice (1.8 ppm in feed) for 90 days resulted in a reduction in body weight gain after 60 days and inhibition of erythrocyte cholinesterase activity after 90 days. Increased levels of serum glutamic oxaloacetic transaminase and alkaline phosphatase were also observed. The results strongly suggest that bean-bound malathion residues can cause adverse biological effects in mice.

The role of non-specific esterases in insecticide resistance to malathion in the diamondback moth Plutella xylostella

1. 1. Esterases play an important role in the mechanism of resistance to malathion in the diamondback moth Plutella xylostella. 2. 2. These enzymes metabolise malathion to less toxic metabolites such as malathion monocarboxylic acid and malathion dicarboxylic acid. 3. 3. The rate of metabolism to nontoxic compounds is more rapid in the resistant strain compared with the susceptible strain. 4. 4. Selection of the susceptible strain with malathion over eight generations gives rise to an increased resistance to malathion that can be correlated with an increase in esterase activity particularly carboxylesterase.

Body distribution of malathion and its metabolites in a fatal poisoning by ingestion.

Eight autopsy samples from an individual who had ingested a large amount of malathion were analyzed fo four components: intact pesticide, malaoxon, malathion monocarboxylic acid (MCA), and malathion dicarboxylic acid (DCA). Malathion was present in all samples except liver. Highest concentrations were found in the gastric contents (8621 ppm) and adipose tissue (76.4 ppm). Malaoxon was identified in some tissues at very low levels; a significant amount was found only in fat (8.2 ppm). The MCA and DCA were detected in all tissue. The former was found in greater abundance: 221 ppm in bile, 106 ppm in kidney, and 103 ppm in the gastric contents.

The biochemical nature of malathion resistance in Anopheles stephensi from Pakistan

Malathion resistance in Anopheles stephensi from Pakistan was synergized by triphenyl phosphate, primarily a carboxylesterase inhibitor. There was a slight degree of antagonism with piperonyl butoxide. The major metabolite of malathion in larvae of both the resistant and susceptible strains was malathion monocarboxylic acid. Resistant larvae produced about twice as much of this product as the susceptible larvae. This suggests that a qualitative or a quantitative change in a carboxylesterase enzyme may be the basis of malathion resistance in this strain. Analysis of general esterase levels to α- and β-naphthyl acetate showed that there was no quantitative change in the amount of carboxylesterase enzyme present in the resistant strain as compared to the susceptible.

Structure assignment to biologically produced malathion monocarboxylic acid isomers with 13C-nuclear magnetic resonance

Chemical synthesis of malathion α- and β-monocarboxylic acid yields a mixture of the two structural isomers. These two isomers were separated by preparative anion-exchange chromatography on QAE-Sephadex. 13C-Nuclear magnetic resonance of the pure components shows that the main product is the β-isomer, with the α-isomer being present in much smaller quantities. This result was used for identification of hydrolytic malathion metabolites produced by rat tissues. On incubation of malathion with rat liver fractions in vitro it was found that α- and β-monoacid are formed in a ratio of 3:2, whereas this ratio is 9:2 for the metabolites excreted into the urine after intraperitoneal injection of malathion in rats.

Degradation of malathion by salt-marsh microorganisms

Numerous bacteria from a salt-marsh environment are capable of degrading malathion, an organophosphate insecticide, when supplied with additional nutrients as energy and carbon sources. Seven isolates exhibited ability (48 to 90%) to degrade malathion as a sole carbon source. Gas and thin-layer chromatography and infrared spectroscopy confirmed malathion to be degraded via malathion-monocarboxylic acid to the dicarboxylic acid and then to various phosphothionates. These techniques also identified desmethyl-malathion, phosphorthionates, and four-carbon dicarboxylic acids as degradation products formed as a result of phosphatase activity.