Quantitative Relationship between Naphthalene Catabolic Gene Frequency and Expression in Predicting PAH Degradation in Soils at Town Gas Manufacturing Sites

The inability to monitor in situ expression of biodegra-dative genes to predict rates of pollutant degradation or to evaluate the efficacy of engineering applications of bioremediation in complex environments such as contaminated soils has limited the routine acceptance of this technology in hazardous waste management. To overcome this limitation, an approach has been developed to measure catabolic gene expression in PAH-contaminated soils. In soils populated with as few as 10⁶ naphthalene degradative bacteria g⁻¹, in situ isolation and quantitation of mRNA levels was achieved for the NAH7 naphthalene dioxygenase (nahA) gene. NahA transcript levels correlated positively with [¹⁴C] naphthalene mineralization rates, soil naphthalene concentration, and nahA gene frequency.