Table 2.

Exogenous addition of Mn²⁺ and Zn²⁺ increases the intracellular Mn²⁺ and Zn²⁺ concentrations^a

Medium	Mean intracellular metal content ± SD (μmol/g, dry wt)
	Mn2+	Zn2+	Mn2+/Zn2+ ratio
BSK-II	0.18 ± 0.08	0.93 ± 0.14	1:5
BSK-II Chelex	0.03 ± 0.01	0.60 ± 0.02	1:20
+ 10 μM MnCl2	0.53 ± 0.19	0.45 ± 0.06	1
+ 10 μM ZnSO4	0.04 ± 0.02	1.20 ± 0.11	1:30
+ 100 μM ZnSO4	0.01 ± 0.01	1.82 ± 0.06	1:182
+ 10 μM MnCl2 + 10 μM ZnSO4	0.69 ± 0.16	0.68 ± 0.21	1
+10 μM MnCl2 + 100 μM ZnSO4	0.35 ± 0.10	1.36 ± 0.19	1:4

^aB. burgdorferi strain 297 was cultivated at 37°C to stationary phase, and intracellular metal contents from two separate experiments with three independent cultures were determined by ICP-MS. Bold values are significantly different from those of the corresponding metal from Chelex-treated BSK-II (P < 0.05). One-way ANOVA with Dunnett's multiple-comparisons test was used to determine significance.