A mutant of Zymomonas mobilis ZM4 capable of ethanol production from glucose in the presence of high acetate concentrations.

Growth of Zymomonas mobilis ZM4 in media containing sodium acetate was inhibited above 12 g sodium acetate/l at pH 5.0. Following mutagenesis of ZM4, an acetate-tolerant strain was isolated in continuous culture that grew in the presence of 20 g sodium acetate/l at pH 5.0. In continuous culture with complete cell recycle at 30 degrees C and pH 5.4 using media containing 110 g glucose/l, the maintenance energy coefficient (m) for the mutant was found to increase from 1.9 g glucose/g cell dry wt. h at 12 g sodium acetate/l up to 3.9 g/g. h at 20 g/l.