Acetate stimulates atmospheric CH4 oxidation by an alpine tundra soil

Experiments were conducted to determine the effects of various carbon substrates 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 300 to 1192.8 (+/-97.2) and 1036.8 (+/-33.6) pg C (g d.w.)(-1)h(-1), respectively. In contrast, methanol did not cause an increase in maximal CH4 oxidation rates, but methanol-treated soil maintained peak rates of CH4 oxidation longer than control soil. In parallel with the CH4 data, acetate additions stimulated acetate utilization, whereas methanol did not stimulate methanol utilization in the soil. This indicates that the mechanism by which acetate stimulates soil CH4 oxidation may not be the same as that by which methanol sustains soil CH4 oxidation. Growth of methanotrophs on acetate has not been reported previously. Therefore, these data indicate that either there is a novel strain of methanotroph in this soil, or that acetate stimulates atmospheric CH4 oxidation by increasing methanogenesis, which in turn increases the supply of methane to the methane oxidizers in this soil. (C) 1999 Elsevier Science Ltd. All rights reserved.