Multiplex PCR amplification. Multiplex PCR amplification performed with mixtures of positive-control DNAs. Lanes: M, 100- to 3,000-bp markers; 1, NAH/PHE primers with P. putida G7 and Pseudomonas sp. strain CF600 DNAs; 2, TOL/TOD primers with P. putida HS1 and P. putida F1 DNAs; 3, BPH2/BPH4 primers with P. pseudoalcaligenes KF707 and Rhodococcus sp. strain RHA1 DNAs.