Acetate stimulates atmospheric CH4 oxidation by an alpine tundra soil

Experiments were conducted to determine the effects of various carbon subst rates on the oxidation of atmospheric CH4 by an alpine tundra soil. Acetate , formate, methanol, trimethylamine and yeast extract were tested. Acetate and formate (500 mu g C (g d.w.)(-1)) stimulated CH4 oxidation rates from 3 00 to 1192.8 (+/-97.2) and 1036.8 (+/-33.6) pg C (g d.w.)(-1)h(-1), respect ively. In contrast, methanol did not cause an increase in maximal CH4 oxida tion rates, but methanol-treated soil maintained peak rates of CH4 oxidatio n longer than control soil. In parallel with the CH4 data, acetate addition s stimulated acetate utilization, whereas methanol did not stimulate methan ol utilization in the soil. This indicates that the mechanism by which acet ate stimulates soil CH4 oxidation may not be the same as that by which meth anol sustains soil CH4 oxidation. Growth of methanotrophs on acetate has no t been reported previously. Therefore, these data indicate that either ther e is a novel strain of methanotroph in this soil, or that acetate stimulate s atmospheric CH4 oxidation by increasing methanogenesis, which in turn inc reases the supply of methane to the methane oxidizers in this soil. (C) 199 9 Elsevier Science Ltd. All rights reserved.