Methylmercury: Bacterial Degradation in Lake Sediments
William J. Spangler 1,
James L. Spigarelli 1,
Joseph M. Rose 1, and
Hope M. Miller 1
1 Midwest Research Institute, Kansas City, Missouri 64110
During the first 50 days of a long-term period of incubation of lake sediments with inorganic mercury (Hg2+), low concentrations of methylinercury were observed to build up. Upon continued incubation there was a rapid decrease in amount of methylmercury in the system and a concomitant evolution of volatile inorganic mercury (Hg0). Transfer of the mixed culture to growth media containing methylmercury resulted in the degradation of methylmercury and the volatilization of Hg0. Four bacterial isolates were obtained from the mixed culture which, in pure culture, rapidly degraded methylmercury to methane and Hg0. The presence of methane in head space gases was confirmed by flameionization gas chromatography, and the presence of Hg0 in head space gases was confirmed by mass spectrometry.
