Isolation and identification of microorganisms for the degradation of Dicamba

Krueger, James P.; Butz, Robert G.; Atallah, Y. H.; Cork, Douglas J.

doi:10.1021/jf00086a057

Cited by 51 publications

(46 citation statements)

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“…Bacterial Strain and Culture Medium-P. maltophilia, strain DI-6, was originally isolated from a soil sample collected near a storm water retention pond at a dicamba manufacturing plant in Beaumont, TX (6). Cells were grown in reduced chloride medium (6) amended with either filter-sterilized 5 mM dicamba or with autoclaved glucose (2 mg/ml) and casamino acids (2 mg/ml) as the carbon source.…”

Section: Methodsmentioning

confidence: 99%

“…Studies with different soil types treated with dicamba have demonstrated that 3,6-dichlorosalicylic acid (DCSA), 1 a compound without herbicidal activity, is a major product of the microbial degradation process (2,3,5). Soil samples taken from a single site exposed to dicamba for several years yielded a number of bacterial species capable of utilizing dicamba as a sole carbon source (6). These soil microorganisms could completely mineralize dicamba to carbon dioxide, water, and chloride ion (7).…”

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confidence: 99%

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A Three-component Dicamba O-Demethylase from Pseudomonas maltophilia, Strain DI-6

Herman¹,

Behrens

Chakraborty

et al. 2005

Journal of Biological Chemistry

118

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Dicamba O-demethylase is a multicomponent enzyme from Pseudomonas maltophilia, strain DI-6, that catalyzes the conversion of the widely used herbicide dicamba (2-methoxy-3,6-dichlorobenzoic acid) to DCSA (3,6-dichlorosalicylic acid). We recently described the biochemical characteristics of the three components of this enzyme (i.e. reductase DIC , ferredoxin DIC , and oxygenase DIC ) and classified the oxygenase component of dicamba O-demethylase as a member of the Rieske nonheme iron family of oxygenases. In the current study, we used N-terminal and internal amino acid sequence information from the purified proteins to clone the genes that encode dicamba O-demethylase. Two reductase genes (ddmA1 and ddmA2) with predicted amino acid sequences of 408 and 409 residues were identified. The open reading frames encode 43.7-and 43.9-kDa proteins that are 99.3% identical to each other and homologous to members of the FAD-dependent pyridine nucleotide reductase family. The ferredoxin coding sequence (ddmB) specifies an 11.4-kDa protein composed of 105 residues with similarity to the adrenodoxin family of [2Fe-2S] bacterial ferredoxins. The oxygenase gene (ddmC) encodes a 37.3-kDa protein composed of 339 amino acids that is homologous to members of the Phthalate family of Rieske non-heme iron oxygenases that function as monooxygenases. Southern analysis localized the oxygenase gene to a megaplasmid in cells of P. maltophilia. Mixtures of the three highly purified recombinant dicamba O-demethylase components overexpressed in Escherichia coli converted dicamba to DCSA with an efficiency similar to that of the native enzyme, suggesting that all of the components required for optimal enzymatic activity have been identified. Computer modeling suggests that oxygenase DIC has strong similarities with the core ␣ subunits of naphthalene 1,2-dioxygenase. Nonetheless, the present studies point to dicamba O-demethylase as an enzyme system with its own unique combination of characteristics.The herbicide dicamba (2-methoxy-3,6-dichlorobenzoic acid) has been used to effectively control broadleaf weeds in crops such as corn and wheat for almost 40 years. Like a number of other chlorinated organic compounds, dicamba does not persist in the soil because it is efficiently metabolized by a consortium of soil bacteria under both aerobic and anaerobic conditions (1-4). Studies with different soil types treated with dicamba have demonstrated that 3,6-dichlorosalicylic acid (DCSA), 1 a compound without herbicidal activity, is a major product of the microbial degradation process (2, 3, 5). Soil samples taken from a single site exposed to dicamba for several years yielded a number of bacterial species capable of utilizing dicamba as a sole carbon source (6). These soil microorganisms could completely mineralize dicamba to carbon dioxide, water, and chloride ion (7). Studies on the metabolism of dicamba in the cells of one of these bacteria, the DI-6 strain of Pseudomonas maltophilia, showed that DCSA is a major degradation product (7,8).We have be...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

A Three-component Dicamba O-Demethylase from Pseudomonas maltophilia, Strain DI-6

Herman¹,

Behrens

Chakraborty

et al. 2005

Journal of Biological Chemistry

118

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“…Dicamba was chemically stable but did not persist in soil and water, suggesting that its dissipation in the environment was biologically mediated (6,7,8,9). Several dicamba-utilizing strains have been isolated, including the aerobic strains Stenotrophomonas (formerly Pseudomonas) maltophilia DI-6 (6), Sphingomonas sp.…”

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confidence: 99%

“…Ndbn-20 (11) and the anaerobic strain Moorella thermoacetica (7). The first step in the degradation of dicamba in these strains was demethylation to generate the herbicidally inactive metabolite 3,6-dichlorosalicylic acid (DCSA) (6,9). To date, two types of dicamba demethylation systems have been documented.…”

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confidence: 99%

A Tetrahydrofolate-Dependent Methyltransferase Catalyzing the Demethylation of Dicamba in Sphingomonas sp. Strain Ndbn-20

Yao

Zhang

et al. 2016

Appl Environ Microbiol

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Sphingomonas sp. strain Ndbn-20 degrades and utilizes the herbicide dicamba as its sole carbon and energy source. In the present study, a tetrahydrofolate (THF)-dependent dicamba methyltransferase gene, dmt, was cloned from the strain, and three other genes, metF, dhc, and purU, which are involved in THF metabolism, were found to be located downstream of dmt. A transcriptional study revealed that the four genes constituted one transcriptional unit that was constitutively transcribed. Lysates of cells grown with glucose or dicamba exhibited almost the same activities, which further suggested that the dmt gene is constitutively expressed in the strain. Dmt shared 46% and 45% identities with the methyltransferases DesA and LigM from Sphingomonas paucimobilis SYK-6, respectively. The purified Dmt catalyzed the transfer of methyl from dicamba to THF to form the herbicidally inactive metabolite 3,6-dichlorosalicylic acid (DCSA) and 5-methyl-THF. The activity of Dmt was inhibited by 5-methyl-THF but not by DCSA. The introduction of a codon-optimized dmt gene into Arabidopsis thaliana enhanced resistance against dicamba. In conclusion, this study identified a THF-dependent dicamba methyltransferase, Dmt, with potential applications for the genetic engineering of dicamba-resistant crops. IMPORTANCEDicamba is a very important herbicide that is widely used to control more than 200 types of broadleaf weeds and is a suitable target herbicide for the engineering of herbicide-resistant transgenic crops. A study of the mechanism of dicamba metabolism by soil microorganisms will benefit studies of its dissipation, transformation, and migration in the environment. This study identified a THF-dependent methyltransferase, Dmt, capable of catalyzing dicamba demethylation in Sphingomonas sp. Ndbn-20, and a preliminary study of its enzymatic characteristics was performed. Introduction of a codon-optimized dmt gene into Arabidopsis thaliana enhanced resistance against dicamba, suggesting that the dmt gene has potential applications for the genetic engineering of herbicide-resistant crops.

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“…Although most of these compounds have been developed, tested, and found safe to use according to label specifications, there is still some concern about the environmental risks associated with their use. Some of the older compounds initially introduced, e.g., DDT, [2,2-bis(4-chlorophenyl)-l,l,l-trichloroethane], aldrin [1,2,3, 4,10,10,hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5,8dimethanonaphthalene], chlordane [ 1,2,4,5,6,7,8,8-octachlor-2,3,3a,4,7,7a-hexahydro-4,7-methanodiane], etc., were highly persistent and bioaccumulated in food chains. However in most countries, their use has been curtailed, upon learning of their environmental hazards.…”

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Pesticide Metabolism in Plants and Microorganisms: An Overview

Hoagland

Zablotowicz

Hall

2000

ACS Symposium Series

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Understanding pesticide metabolism in plants and microorganisms is a key component for the development, the safe and efficient utilization of these compounds, and for bioremediation of these chemicals in contaminated soil and water. Selective metabolism of pesticides in non-target species (e.g., crop plants) and sensitivity in target species (e.g. weeds, insects and pathogen pests), is the basis of chemical pest control. Pesticide biotransformations may occur via metabolism or co-metabolism. Metabolism of a given pesticide in plants and microorganisms is generally a multi-step process. Individual components of such degradation/detoxification pathways include: oxidation, reduction, hydrolysis and conjugation. Pathway diversity depends on the chemical structure of the xenobiotic compound, the organism, environmental conditions, and metabolic factors regulating expression of these biochemical pathways. Knowledge of these enzymatic processes, especially concepts related to mechanism of action, resistance, selectivity, tolerance, and environmental fate has advanced pesticide science. One example is the development of herbicide tolerant crops. Advances in pesticide metabolism have also been facilitated by use of improved analytical techniques, molecular biological approaches, and immunological tools.The inception of synthetic organic compounds for control of insect, microbial, and weed pests began over sixty years ago. Pesticides have transformed agricultural production to provide the quality and quantity of food and fiber necessary for an exponentially increasing world population. Since that time, millions of tons of 2

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Isolation and identification of microorganisms for the degradation of Dicamba

Cited by 51 publications

References 9 publications

A Three-component Dicamba O-Demethylase from Pseudomonas maltophilia, Strain DI-6

A Three-component Dicamba O-Demethylase from Pseudomonas maltophilia, Strain DI-6

A Tetrahydrofolate-Dependent Methyltransferase Catalyzing the Demethylation of Dicamba in Sphingomonas sp. Strain Ndbn-20

Pesticide Metabolism in Plants and Microorganisms: An Overview

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