Strain 17A1T grew as a chemoautotroph in a modified medium Mc without vitamins and yeast extract. Growth was stimulated by the addition of acetate (5 mM), vitamins (5 ml l21), yeast extract (0.2 g l21) or rumen fluid (5 ml l21). Strain 17A1T utilized H2/CO2 and methanol +H2 for growth (Table 1) and methane production but did not grow on methanol (30 mM), methylamine (20 mM)+H2, formate (30 mM), acetate (30 mM), 2-propanol (20 mM) or isobutanol (20 mM)