Table 4.

Comparison of intracellular TPP levels in wild-type T. denticola and the ΔtbpA mutant^a

TPP concn in TA medium	Mean intracellular TPP concn (nM) ± SEM in:
	Wild-type T. denticola	ΔtbpA mutant
100 nM	94.43 ± 8.96
10 μM	184.85 ± 4.52	94.49 ± 6.97
50 μM	258.39 ± 7.21	230.34 ± 4.3

^aThe two strains were cultivated in TA medium containing different concentrations of TPP (100 nM, 10 μM, and 50 μM). Three independent assays were conducted, and the intracellular concentrations of TPP were determined. The ΔtbpA mutant failed to grow at the low concentration of TPP (100 nM).