Methanol as the primary methanogenic and acetogenic precursor in the cold Zoige wetland at Tibetan plateau.

Previous studies suggested that methanol and acetate were the likely methanogenic precursors in the cold Zoige wetland. In this study, the contribution of the two substances to methanogenesis and the conversion in Zoige wetland were analyzed. It was determined that methanol supported the highest CH(4) formation rate in the enrichments of the soil grown with Eleocharis valleculosa, and even higher at 15 degrees C than at 30 degrees C; while hydrogenotrophic methanogenesis was higher at 30 degrees C. Both methanol- and acetate-using methanogens were counted at the highest (10(7) g(-1)) in the soil, whereas methanol-using acetogens (10(8) g(-1)) were ten times more abundant than either methanol- or acetate-using methanogens. Both methanol and acetate were detected in the methanogenesis-inhibited soil samples, so that both could be the primary methanogenic precursors in E. valleculosa soil. However, the levels of methanol and acetate accumulated in 2-bromoethane-sulfonate (BES)- and CHCl(3)-treated soils were in reverse, i.e., higher methanol in CHCl(3)- and higher acetate in BES-treated soil, so that methanol-derived methanogenesis could be underestimated due to the consumption by acetogens. Analysis of the soil 16S rRNA genes revealed Acetobacterum bakii and Trichococcus pasteurii to be the dominant methanol-using acetogens in the soil, and a strain of T. pasteurii was isolated, which showed the high conversion of methanol to acetate at 15 degrees C.