Metabolism of 2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid and 2-methylphenoxyacetic acid by Alcaligenes eutrophus JMP 134

Abstract

Abstract. Of eleven substituted phenoxyacetic acids tested, only three (2,4-dichloro-, 4-chloro-2-methyl-and 2-methylphenoxyacetic acid) served as growth substrates for Alcaligenes eutroplws JMP 134. Whereas only one enzyme seems to be responsible for the initial cleavage of the ether bond, there was evidence for the presence of three different phenol hydroxylascs in this strain. 3,5-Dichlorocatechol and 5-ch loro-3-methylca techol, metabolites of the degradation of 2,4-diehlorophenoxyacetic acid and 4-cWoro-2-methylphenoxyacetic acid, respectively, were exclusively metabolized via the ortho-cleavage pathway. 2-Methylphenoxy. acetic acid-grown cells showed sim ultaneous induction of meta-and ortho-cleavage enzymes. Two catechol 1,2-dioxygcnases responsible for o rlho-cleavage of the intcr~ mediate catechols were partially purified and characterized. One of these enzymes converted 3,5-dichlorocatechol considerably faster than catechol or 3-chlorocatechoL A new enzyme for the cycloisomerisation ofmuconates was found , which exhibited high activity against the ring-cleavage products of 3,5-dichlorocatcchol and 4-chlorocatechol, but low activities against 2-chloromuconate and muconate.

A Gene Cluster Involved in Degradation of Substituted Salicylates viaorthoCleavage inPseudomonassp. Strain MT1 Encodes Enzymes Specifically Adapted for Transformation of 4-Methylcatechol and 3-Methylmuconate

“…Clearly, MT1 uses a similar pathway for degradation of 4-methylmuconolactone by initially isomerizing it into 3-methylmuconolactone. However, in contrast to the situation with C. necator, which also harbors catechol meta cleavage pathways (21,22) and is reported to degrade methylaromatics by both intra-and extradiol cleavage (40,41), MT1 metabolizes methylsalicylates exclusively via the ortho cleavage pathway (Fig. 4).…”

Metabolism of 5‐Chlorosubstituted Muconolactones

“…Similarly, transformation of 5-chloromuconolactone (200 pM) was measured spectrophotometrically at 280 nm using 1-10 pg protein (crude extract or 0.002-0.02 pg purified muconolactone isomerase in a total volume of 100 pl). Muconate cycloisomerase, dienelactone hydrolase, as well as rnaleylacetate reductase were assayed as described by Pieper et al (1988). Activities of dienelactone hydrolase with substrate concentrations higher than 100 pM were followed at 305 nm.…”

“…2-Methyldienelactone was proposed to be a metabolite of both 4-chloro-2-methylphenoxyacetate and 4-chlorotoluene metabolism (Gaunt and Evans, 1971b; Haigler and Spain, 1989; Pieper et al, 1988). However, no detailed data on the specificity of dienelactone hydrolases involved in chloroaromatic metabolism by Gram-negative microorganisms (Schlomann et al, 1990b) were available, even though these enzymes were believed to be rather unspecific and to tolerate substituents in the 2-position (Haigler and Spain, 1989 ;Pieper et al, 1988Pieper et al, , 1991. Dienelactone hydrolase was partially purified from 2,4-dichlorophenoxyacetate grown cells of A. eutrophus JMP 134.…”

“…1 D). In the course of metabolism of other chloromethylcatechols, in analogy to the metabolism of chlorocatechols, dehalogenation during cycloisomerization to form methyl-substituted dienelactones as intermediates has been postulated (Gaunt and Evans, 1971a,b;Haigler and Spain, 1989;Pieper et al, 1988). However, despite the assumption of the easy degradation of methyldienelactones little detailed information is actually available on their further transformation.…”

Delftia acidovoransMC1 Resists High Herbicide Concentrations — a Study of Nutristat Growth on (RS)-2-(2,4-Dichlorophenoxy)propionate and 2,4-Dichlorophenoxyacetate

“…They have been shown to be degradable by microbes, as was found for a number of bacterial strains with respect to 2,4-D, [2][3][4][5][6][7] but also holds for the enantiomers of (RS)-2-(2,4-dichlorophenoxy)propionate [(RS)-2,4-DP] with e.g. strains Sphingomonas herbicidovorans MH, 8,9) Rhodoferax sp.…”