Effect of heavy metals on the growth of a methanogen in pure culture and coculture with a sulfate-reducing bacterium

The sensitivity of a methanogen and sulfate-reducing bacterium isolated fro m a sea-based landfill site to Cd2+ and Cu2+ was studied. Methanogens and s ulfate-reducing bacteria in leachates of the waste disposal site were enume rated using the MPN method. Methanobacterium thermoautotrophicum KHT-2, iso lated from the leachate, could not grow at 0.5 mM Cd2+ or 1.0 mM Cu2+. Desu lfotomaculum sp. RHT-3, isolated from the same leachate, was able to insolu bilize 3.0 mM Cd2+ or 2.0 mM Cu2+ by production of hydrogen sulfide. When s trains KHT-2 and RHT-3 were cultured together in the presence of the heavy metals, strain KHT-2 could grow at high heavy metal concentrations after in solubilization of the metals by strain RHT-3.