Factors Affecting the Methanogenic Activity of Methanothrix soehngenii VNBF.

Methane production by Methanothrix soehngenii VNBF grown on acetate (50 mM) as the sole carbon and energy source was influenced by the addition of Fe, trace elements, and pesticides. The addition of Fe and trace elements significantly enhanced the rate of CH(4) production. The addition of pesticides in the early growth phase caused complete inhibition. However, less inhibition was noted when pesticides were added during early exponential growth phase. Addition to culture tubes of Co, Ni, or Mo at 2 muM produced 64, 41, or 17%, respectively, more CH(4) than that produced in tubes lacking the corresponding trace element. A concentration of more than 5 muM of these trace elements in the medium resulted in decreased CH(4) production, presumably because of toxic effects.