Characterization of (R/S)‐mecoprop [2‐(2‐methyl‐4‐chlorophenoxy) propionic acid]‐degrading Alcaligenes sp. CS1 and Ralstonia sp. CS2 isolated from agricultural soils

Abstract

The herbicide mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid] is widely applied to corn fields in order to control broad-leaved weeds. However, it is often detected in groundwater where it can be a persistent contaminant. Two mecoprop-degrading bacterial strains were isolated from agricultural soils through their capability to degrade (R/S)-mecoprop rapidly. 16S rDNA sequencing of the isolates demonstrated that one was closely related to the genera Alcaligenes sp. (designated CS1) and the other to Ralstonia sp. (designated CS2). Additionally, these isolates demonstrated ability to grow on other related herbicides, including 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA [4-chloro-2-methyl phenoxy acetic acid] and (R/S)-2,4-DP [2-(2,4-dichlorophenoxy)propionic acid] as sole carbon sources. tfdABC gene-specific probes derived from the 2,4-D-degrading Variovorax paradoxus TV1 were used in hybridization analyses to establish whether tfd-like genes are present in mecoprop-degrading bacteria. Hybridization analysis demonstrated that both Alcaligenes sp. CS1 and Ralstonia sp. CS2 harboured tfdA, tfdB and tfdC genes on plasmids that have approximately > 60% sequence similarity to the tfdA, tfdB and tfdC genes of V. paradoxus. It is therefore likely that tfd-like genes may be involved in the degradation of mecoprop, and we are currently investigating this further.

Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater

“…and a Ralstonia sp. (44), Alcaligenes denitrificans (45), and a number of Sphingomonas sp. strains (46) isolated from soil.…”

Uptake Kinetics of 2,4-Dichlorophenoxyacetate byDelftia acidovoransMC1 and Derivative Strains: Complex Characteristics in Response to pH and Growth Substrate

“…P230, 17,18) and several less well described strains. [19][20][21][22] They show in general a broader spectrum of productive, i.e., growth-associated, degradation, which includes, e.g., 2,4-D and MCPA. This capability is attributed to the expression of two -ketoglutaratedependent dioxygenases, called (R)-2,4-dichlorophenoxypropionate/-ketoglutarate-dioxygenase (RdpA) and (S)-2,4-dichlorophenoxypropionate/-ketoglutarate-dioxygenase (SdpA), which exhibit enantio-and substrate specific properties.…”

Localization and Characterization of Two Novel Genes Encoding Stereospecific Dioxygenases Catalyzing 2(2,4-Dichlorophenoxy)propionate Cleavage in Delftia acidovorans MC1

“…The ability to degrade the phenoxyacetate herbicides is widespread among bacteria (16). In contrast, breakdown of the structurally very similar chiral phenoxypropionate derivatives is far less widespread, and only few strains able to mineralize these compounds have been described (9,21,30,35,42,50).…”