CONSERVATION OF REGULATORY AND STRUCTURAL GENES FOR A MULTICOMPONENT PHENOL HYDROXYLASE WITHIN PHENOL-CATABOLIZING BACTERIA THAT UTILIZE A META-CLEAVAGE PATHWAY

Pseudomonas sp. strain CF600 can degrade phenol and some of its methyl ated derivatives via a plasmid (pVI150)-encoded pathway. The metabolic route involves hydroxylation by a multi-component phenol hydroxylase and a subsequent meta-cleavage pathway. All 15 structural genes involv ed are clustered in an operon that is regulated by a divergently trans cribed transcriptional activator. The multi-component nature of the ph enol hydroxylase is unusual since reactions of this type are usually a ccomplished by single component flavoproteins. We have isolated and an alysed a number of marine bacterial isolates capable of degrading phen ol and a range of other aromatic compounds as sole carbon and energy s ources. Southern hybridization and enzyme assays were used to compare the catabolic pathways of these strains and of the archetypal phenol-d egrader Pseudomonas U, with respect to known catabolic genes encoded b y Pseudomonas CF600. All the strains tested that degraded phenol via a meta-cleavage pathway were found to have DNA highly homologous to eac h of the components of the multi-component phenol hydroxylase. Moreove r, DNA of the same strains also strongly hybridized to probes specific for pVI150-encoded meta-pathway genes and the specific regulator of i ts catabolic operon. These results demonstrate conservation of structu ral and regulatory genes involved in aromatic catabolism within strain s isolated from diverse geographical locations (UK, Norway and USA) an d a range of habitats that include activated sludge, sea water and fre sh-water mud.