TABLE 1.

Specific Hg methylation rates by pure culture SRB

Species	Hg methylation rate (pM MeHg h−1)a
	Assayb	Controlc
Incomplete oxidizers
D. africanus	64.4 ± 28.1	<DL
D. vulgaris subsp. vulgaris Marberg	<DL	<DL
D. propionicus 1pr3	53.1 ± 7.32	<DL
D. propionicus MUD	141 ± 31.2	<DL
Complete oxidizers
D. multivorans 1be1	44.5 ± 16.9	<DL
D. curvatus	<DL	<DL

^aValues are averages ± standard deviation of three replicate assays. The average method detection limit (DL) = 6.2 pM MeHg h⁻¹ (n = 10).

^bLive cultures were incubated with 5 nM HgCl₂ for 5 h. Rates were corrected for the average blank MeHg concentration.

^cAutoclaved cultures were incubated with 5 nM HgCl₂ for 5 h.