TABLE 2.

Comparison of 16S rDNA gene template and PCR product ratios in simultaneous PCR amplifications of three bacterial genomes with degenerate primers^a

Prepn	Species ratiosb
	B. subtilis/ V. fischeri	B. subtilis/ V. anguillarum	V. fischeri/ V. anguillarum
Genomic mixture	1.0 ± 0.06	1.0 ± 0.08	1.0 ± 0.07
PCR mixture	2.3 ± 0.18	3.2 ± 0.29	1.4 ± 0.13
PCR 1	2.3 ± 0.12	3.7 ± 0.18	1.6 ± 0.09
PCR 2	2.2 ± 0.13	3.2 ± 0.21	1.4 ± 0.09
PCR 3	2.5 ± 0.17	3.2 ± 0.31	1.3 ± 0.12
PCR 4	2.0 ± 0.15	3.5 ± 0.35	1.8 ± 0.15
PCR 5	3.5 ± 0.25	3.5 ± 0.30	1.0 ± 0.08

^aThe data were generated by dot blotting and hybridization with species-specific probes of equal amounts of template DNAs from the three species (genomic mixture), a mixture of 10 replicate PCR amplifications (25 cycles) performed with the genomic mixture (PCR mixture), and a subsample of 5 of the 10 replicate PCR amplifications (PCR 1 to 5). 

^bMeans ± standard deviations were calculated from data for nine replicate dots for each of the samples which was hybridized with the specific probes and quantified by phosphorimaging. Subsequently, the PCR product signals were normalized to the genomic mixture signal by using a constant factor for each species pair (see text).