Treatment of both Candida apicola IMET 43747 and Candida bombicola ATCC 22214 with N-methyl-N'-nitro-N-nitroso guanidine resulted in formation of auxotrophic mutants and cytochrome oxidase negative mutants. The deficiency of intact cytochrome oxidase did not affect the ability to produce sophorose lipid. This indicates that intact mitochondrial energy supplying system is not necessary for the production of the extracellular sophorose lipids by both Candida yeasts.