FIG. 3.

RT-PCR amplification of nahAc mRNA transcripts isolated from cells in groundwater at the coal tar-contaminated site, using PCR reverse primer Ac596R with three forward primers. Reverse transcriptase was omitted from the cDNA synthesis reactions in lanes 1 to 3, demonstrating that products in lanes 4 to 6 (primers Ab248F, Ac114F, and Ac307F, respectively) were not derived from DNA sequences contaminating the RNA preparation. Groundwater-derived amplicons (lanes 4 to 6) were identical in size to those from RNA of naphthalene-grown P. putida G7 cells (lanes 7 to 9; primers Ab248F, Ac114F, and Ac307F, respectively).