Oxidative degradation of aromatic hydrocarbons by microorganisms. II. Metabolism of halogenated aromatic hydrocarbons

Abstract

Pseudomonas putida, grown with toluene as sole source of carbon, oxidized chloro-, bromo-, iodo-, and fluorobenzenes to their respective 3-halogenated catechol derivatives. The dihydroxy compounds from the first three substrates above were identified by isolation and comparison with synthetic compounds. The investigation of the metabolism of ^-chlorotoluene resulted in the isolation of two compounds which have Our continued interest in the mechanism of oxygen fixation into the aromatic nucleus led us to try to isolate the early intermediates in the degradation of several aromatic compounds. Since both toluene and benzene are metabolized at an extremely rapid rate by Pseudomonas putida (Gibson et al., 1968), with little accumulation of reaction products, it seemed probable that cooxidation (Leadbetter and Foster, 1960; Davis and Raymond, 1961) might be of use in our studies. Halogenated aromatic derivatives were chosen as potential partially metabolizable intermediates. The presence of a halogen atom seems to greatly reduce the biodegradability of many aromatic compounds (Alexander and Lustigman, 1966;Ichihara et al., 1962).This paper describes the isolation and identification of the products formed from chloro-, bromo-, iodo-, and fluorobenzenes and also p-chlorotoluene when these substrates are incubated with cells of P. putida, grown with toluene as the sole source of carbon. Materials and Methods1Organism and Growth Conditions. P. putida was grown in media whose composition has been described previously (Gibson et al., 1968).

Degradation of chloroaromatics by Pseudomonas putida GJ31: assembled route for chlorobenzene degradation encoded by clusters on plasmid pKW1 and the chromosome

“…These enzymes are typically of relatively broad substrate specificity (Gibson & Parales, 2000) and, as an example, toluene dioxygenase of P. putida F1 accepts, besides toluene, also chlorobenzene, p-chlorotoluene and 1,2-dichlorobenzene as substrates (Beil et al, 1998;Gibson et al, 1968).…”

“…Whereas CbzAb and CbzB were identical to TodC2 and TodB, respectively, CbzAa, CbzAd and CbzD differed from the orthologous Tod proteins by only a single amino acid each. As these differences are localized in regions not crucial for protein performance (Friemann et al, 2009) or constitute conservative amino acid differences (Hülsmeyer et al, 1998), it can be assumed that all encoded proteins are functional and similar in substrate specificity to those described from strain F1 and are capable of transforming chlorobenzene to 3-chlorocatechol (Gibson et al, 1968) sufficiently to allow growth on chlorobenzene (Ravatn et al, 1998) (see Fig. 4).…”

Stereochemical course of two arene-cis-diol dehydrogenases specifically induced in Pseudomonas putida

“…The next enzymic reaction dehydrogenates these cyclic cis-diols, with aromatization yielding catechols for ring cleavage. H was transferred from both the 2-and 3-C atoms of (2S,3R)-p-toluate-2,3-dihydrodiol with specifically deuterated species in approximately equal amounts; and (iii) the unexpected lack of stereo-and regioselectivity of p-toluate-2,3-diol dehydrogenase was supported by kinetic isotope effect studies.Most nonhydroxylated arenes biodegraded by bacteria are dihydroxylated initially, in NADH-dependent reactions, to give cis-1,2-diol cyclohexadiene intermediates (10,(12)(13)(14)17). The second reaction of these catabolic pathways is usually an NADdependent dehydrogenation with concomitant rearomatization of the ring to give a catechol.…”

The Bacterial Degradation of 5‐Amino‐4‐chloro‐2‐phenyl‐3(2H)‐pyridazinone

“…Catechol compounds have been found to be intermediates, directly formed from the dihydroxycyclohexadiene compounds [16,17]. Jn the course of this work a catechol compound was never detectable in the medium of the pyrazon-degrading bacteria.…”