One of the erg9 mutants, MBNA1-13, was compared to the parent strain in a fed batch fermentation experiment. Growth rate and cell yield of the erg9 mutant were reduced relative to the parent strain. While farnesol accumulation was not detectable in the parent strain, the erg9 mutant accumulated farnesol to more than 2.7 g/L, with approximately half found in the growth medium and the remainder found associated with the cells.