Metabolism of <i>p</i>- and <i>m</i>-xylene by species of <i>Pseudomonas</i>

Abstract

Species of Pseudomonas isolated from soil could utilize m- or p-xylene as the sole carbon source. The respective toluic acids of the xylenes were isolated from growth media and from cells suspended in buffer. Cells grown on either hydrocarbon were capable of "meta" type cleavage of catechol and the methylcatechols. A compound whose properties were consistent with the structure of 2-hydroxy-5-methylmuconic semialdehyde was produced when cell-free extracts of p-xylene-grown cells were confronted with 4-methylcatechol. This muconic semialdehyde was present in the growth medium of p-xylene-grown cells and in buffer suspensions of these cells confronted with p-xylene. Paraxylene-grown cells oxidized p-chlorotoluene and 4-chloro-catechol to a compound with a spectrum similar to those of "meta" cleavage products. Chemical isolations and manometric data are consistent with a pathway for the oxidative metabolism of p-xylene which includes p-methylbenzyl alcohol, p-tolualdehyde, p-toluic acid, 4-methylcatechol, and 2-hydroxy-5-methylmuconic semialdehyde.