Naphthalene catabolic genes

Stuart-Keil KG, AM Hohnstock, KP Drees, JB Herrick, EL Madsen (1998) Plasmids responsible for horizontal transfer of naphthalene catabolism genes between bacteria at a coal tar-contaminated site are homologous to pDTGl from Pseudomonas putida NCIB 9816-4. Appl Environ Microbiol 64 3633-3640. 

Wilson and Madsen [152] used the metabolic pathway for bacterial naphthalene oxidation as a guide for selecting l,2-dihydroxy-l,2-dihydronaphthalene as a unique transient intermediary metabolite whose presence in samples from a contaminated field site would indicate active in situ naphthalene biodegradation (Fig. 26). Naphthalene is a component of a variety of pollutant mixtures. It is the major constituent of coal tar [345], the pure compound was commonly used as a moth repellant and insecticide [345], and it is a predominant constituent of the fraction of crude oil used to produce diesel and jet fuels [346]. Prior studies at a coal tar-contaminated field site have focused upon contaminant transport [10,347], the presence of naphthalene catabolic genes [348, 349], and non-metabolite-based in situ contaminant biodegradation [343]. 

The naphthalene catabolic genes are located in most cases on plasmids. In this group the best-studied plasmid is NAH7 of P. putida PpG7. It carries two operons, one of which enables the utilization of naphthalene and the other salicylate. Both operons are turned on by the product of another NAH7 gene, nahR, in the presence... 

Wilson MS, Bakermans C, Madsen EL (1999) In situ, real-time catabolic gene expression extraction and characterization of naphthalene dioxygenase mRNA transcripts from groundwater. Appl Environ Microbiol 65 80-87... 

Figure 2. A) Genetic organization of the pKAl catabolic plasmid. Genes of the upper naphthalene regulatory system encode for proteins that mediate the conversion of naphthalene to salicylate. Salicylate is then further degraded to TCA cycle intermediates. B) In Pseudomonas fluorescens HK44, genes within the lower pathway were replaced with genes of the lux cassette to produce a bioluminescent bioreporter sensitive to naphthalene and salicylate.

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