TABLE 3.

Quantification of arcA expression^a

Strain	Mean expression of arcA ± SD
S. cristatus CC5A	20.24 ± 1.76
S. gordonii DL1	1.45 ± 0.43
S. cristatus ARCAE	0.005 ± 0.001
S. gordonii ARCAE	0.002 ± 0.00
S. cristatus cARCAE	26.27 ± 1.18
S. cristatus dARCAE	4.05 ± 1.36
S. gordonii dARCAE	0.67 ± 0.01
S. gordonii cARCAE	2.20 ± 0.14

^aTranscript levels were measured by real-time PCR, and the relative expression of arcA was normalized by using 23S rRNA. The results shown are means from four independent experiments.