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Pseudomonas sp. strain B13 is a bacterium known to degrade chloroaromatic compounds. The properties to use 3- and 4-chlorocatechol are determined by a self-transferable DNA element, the clc element, which normally resides at two locations in the cell's chromosome. Here we report the complete nucleotide sequence of the clc element, demonstrating the unique catabolic properties while showing its relatedness to genomic islands and integrative and conjugative elements rather than to other known catabolic plasmids. As far as catabolic functions, the clc element harbored, in addition to the genes for chlorocatechol degradation, a complete functional operon for 2-aminophenol degradation and genes for a putative aromatic compound transport protein and for a muiticomponent aromatic ring dioxygenase similar to anthranilate hydroxylase. The genes for catabolic functions were inducible under various conditions, suggesting a network of catabolic pathway induction. For about half of the open reading frames (ORFs) on the clc element, no clear functional prediction could be given, although some indications were found for functions that were similar to plasmid conjugation. The region in which these ORFs were situated displayed a high overall conservation of nucleotide sequence and gene order to genomic regions in other recently completed bacterial genomes or to other genomic islands. Most notably, except for two discrete regions, the clc element was almost 100% identical over the whole length to a chromosomal region in Burkholderia xenovorans LB400. This indicates the dynamic evolution of this type of element and the continued transition between elements with a more pathogenic character and those with catabolic properties.

Research reveals a set of five genes localized to 5.9-kb tfdR-tfdK intergenic region of plasmid pJP4 forming a gene cluster. Data point out that the gene cluster encodes enzymes involved in the conversion of 2,4-dichlorophenol to beta-ketoadipate in Ralstonia eutropha JMP134.

A study was undertaken to determine the unknown characteristics of the transmissible chlorocatechol degradation (clc) gene from the Pseudomonas specie strain B13 utilizing pulse-field gel eletrophoresis, DNA-DNA hybridizations and cosmid mapping. The B13 strain was considered a pseudomonad using the 3-chlorobenzoate as the main source of carbon and energy. Results revealed that clc genes were discovered on a transmissible element and the physical appearance of this element was detected by its tandem amplification in the host strain, P. putida F1.

A study was conducted to examine low-frequency horizontal transfers of chlorocatechol degradative genes from Pseudomonas sp. strain B13 in activated-sludge microcosms. Matings were carried out with cultures pre-grown on Luria-Bertani medium that was washed and resuspended in Z3 mineral medium. The microcosms were characterized by glass reactors and operated at a volume of about 05. liter of culture medium.