Accelerated degradation of thiocarbamate herbicides in Israeli soils following repeated use of vernolate

Tal, A.; Rubin, Baruch; Katan, J.; Aharonson, N.

doi:10.1002/ps.2780250404

Cited by 19 publications

(15 citation statements)

References 25 publications

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“…The half-life times of free EPTC incorporated into sandy soil were 15.5 and 17 days as determined by root and shoot lengths of oat seedlings, respectively (Figures 9 and 10). These data are in agreement with those reported by Tal et al (1989) for EPTC behavior in sandy soils. Using either Mont-EPTC or SepEPTC, with or without MG, did not change the dissipation pattern of the herbicide but resulted in a half-life time 1 week longer than that of free EPTC.…”

Section: T I M E Of Incubation (Weeks)supporting

confidence: 95%

Slow Release of S-Ethyl Dipropylcarbamothioate from Clay Surfaces

Margulies¹,

Stern²,

Rubin³

1994

J. Agric. Food Chem.

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The adsorption/desorption behavior of the volatile herbicide S-ethyl dipropylcarbamothioate (EPTC) to/from montmorillonite and sepiolite was studied. The clays were used as such or with their surface properties modified by adsorption of the cationic dye methyl green (MG). At 30 "C, the half-life time (Tip) of the herbicide in its free form was 10 h, whereas when adsorbed to montmorillonite the T l p was more than 5 days. When EPTC was incorporated into the soil, the T1p values were 4 and 9 days for the free and adsorbed forms, respectively. The interactions between EPTC and clay surface were studied by Fourier-transform infrared spectroscopy. Vibrational spectra revealed two different populations of EPTC in the clay-organic complexes: one in which the molecules are adsorbed, interacting with the clay surface, and another in which they do not interact with the clay, their spectrum being almost identical to that of free EPTC. Coadsorbed MG impairs the EPTC-clay interactions, causing an increase in free EPTC, indicating that free EPTC is released from the organoclay at a rate higher than that of adsorbed EPTC. Oat bioassays showed that the herbicidal activity of clay-complexed EPTC was extended by more than 1 week. These data indicate that clay-EPTC interactions can be employed to improve herbicidal performance of EPTC and to control its release to the environment.

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Section: T I M E Of Incubation (Weeks)supporting

confidence: 95%

Slow Release of S-Ethyl Dipropylcarbamothioate from Clay Surfaces

Margulies¹,

Stern²,

Rubin³

1994

J. Agric. Food Chem.

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“…These compounds are considered hazardous because they potently inhibit acetylcholine esterase (9) and the N-nitrosocarbamates formed are potent mutagens (8). On the other hand, these pesticides generally do not persist in soil for a long time, and the persistence of these compounds in agricultural soil is due to repeated applications (10,38). From these perspectives, an understanding of the degradation mechanism is needed to control the persistence of these pesticides in soil.…”

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confidence: 99%

Nucleotide Sequence and Genetic Structure of a Novel Carbaryl Hydrolase Gene ( cehA ) from Rhizobium sp. Strain AC100

Hashimoto

Fukui

Hayano

et al. 2002

Appl Environ Microbiol

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Rhizobium sp. strain AC100, which is capable of degrading carbaryl (1-naphthyl-N-methylcarbamate), was isolated from soil treated with carbaryl. This bacterium hydrolyzed carbaryl to 1-naphthol and methylamine. Carbaryl hydrolase from the strain was purified to homogeneity, and its N-terminal sequence, molecular mass (82 kDa), and enzymatic properties were determined. The purified enzyme hydrolyzed 1-naphthyl acetate and 4-nitrophenyl acetate indicating that the enzyme is an esterase. We then cloned the carbaryl hydrolase gene (cehA) from the plasmid DNA of the strain and determined the nucleotide sequence of the 10-kb region containing cehA. No homologous sequences were found by a database homology search using the nucleotide and deduced amino acid sequences of the cehA gene. Six open reading frames including the cehA gene were found in the 10-kb region, and sequencing analysis shows that the cehA gene is flanked by two copies of insertion sequence-like sequence, suggesting that it makes part of a composite transposon.Carbamate insecticides such as carbaryl (1-naphthyl N-methylcarbamate) are broad-spectrum insecticides that comprise the major proportion of agricultural pesticides used in today's agricultural industry. These compounds are considered hazardous because they potently inhibit acetylcholine esterase (9) and the N-nitrosocarbamates formed are potent mutagens (8). On the other hand, these pesticides generally do not persist in soil for a long time, and the persistence of these compounds in agricultural soil is due to repeated applications (10, 38). From these perspectives, an understanding of the degradation mechanism is needed to control the persistence of these pesticides in soil.Soil microorganisms are thought to play a significant role in the reduction of pesticides in soil, and many soil bacteria capable of degrading carbamate pesticides have been isolated and characterized (4,6,16,17,21,28). The biochemical characteristics of carbamate pesticide hydrolases have also been reported (5,17,18,20,25). However, little is known about the genes for these enzymes. The mcd gene, which encodes a carbofuran hydrolase, is located on a 100-kb plasmid called pPDL11, and it has been cloned from Achromobacter sp. strain WM111 (41). This gene was shown to be present in many bacteria and to be encoded on a 100-, 105-, 115-, or 124-kb plasmid found in diverse bacteria isolated from geographically distant areas (6, 29). However, the structure of the carbamate insecticide degradative gene has not as yet been reported, although the nucleotide sequence of mcd gene is available (accession no. AF160188).The present study characterizes a carbaryl hydrolase purified from Rhizobium sp. strain AC100. From the result of a plasmid-curing experiment, it was suggested that the carbamate insecticide degradative gene is encoded on the plasmid. We then cloned the degradative gene from the plasmid DNA and determined the nucleotide sequence of the 10-kb region containing the degradative gene. The sequence analysis suggested that the g...

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“…Many authors have suggested that microbial degradation plays an important role in the reduction of the accumulation of the pesticide residues. However, the microbial degradation of the pesticides may be so rapid as to reduce the efficacy against the target pest (9,21). Therefore, much attention has focused on the microbial degradation of carbamate pesticides.…”

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Purification and Characterization of Carbaryl Hydrolase from Blastobacter sp. Strain M501

Hayatsu¹,

Nagata²

1993

Appl Environ Microbiol

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A bacterium capable of hydrolyzing carbaryl (1-naphthyl-N-methylcarbamate) was isolated from a soil enrichment. This bacterium was characterized taxonomically as a Blastobacter sp. and designated strain M501. A carbaryl hydrolase present in this strain was purified to homogeneity by protamine sulfate treatment, ammonium sulfate precipitation, and hydrophobic, anion-exchange, gel filtration, and hydroxylapatite chromatographies. The native enzyme had a molecular mass of 166,000 Da and was composed of two subunits with molecular masses of 84,000 Da. The optimum pH and temperature of the enzyme activity were 9.0 and 45C, respectively. The enzyme was not stable at temperatures above 40°C. The purified enzyme hydrolyzed seven N-methylcarbamate insecticides and also exhibited activity against 1-naphthyl acetate and 4-nitrophenyl acetate.

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Accelerated degradation of thiocarbamate herbicides in Israeli soils following repeated use of vernolate

Cited by 19 publications

References 25 publications

Slow Release of S-Ethyl Dipropylcarbamothioate from Clay Surfaces

Slow Release of S-Ethyl Dipropylcarbamothioate from Clay Surfaces

Nucleotide Sequence and Genetic Structure of a Novel Carbaryl Hydrolase Gene ( cehA ) from Rhizobium sp. Strain AC100

Purification and Characterization of Carbaryl Hydrolase from Blastobacter sp. Strain M501

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