NAH primer specificity confirmation by agarose gel electrophoresis. The specificity of each primer set was confirmed by PCR with positive- and negative-control templates (A), followed by hybridization experiments with gene probes created from positive-control strains (B). Lanes: M, 100- to 3,000-bp markers; 1, P. putida G7; 2, Burkholderia sp. strain DNT; 3, P. putida F1; 4, P. putida HS1; 5, P. putida mt-2.