Decreased susceptibility to antifungals in respiratory-deficient Kluyveromyces lactis mutants.

Decreased susceptibility of K. lactis mutants impaired in the function of cytochrome c, cytochrome c1 and cytochrome-c oxidase to fluconazole, bifonazole and amphotericin B in comparison with the isogenic wild-type strain was observed. Flow cytometry with rhodamine 6G did not show any changes in the accumulation of the dye in the mutant cells compared with the corresponding wild-type strain. Sterol analysis showed similar overall amount of sterols in both wild-type and mutant cells. Taking into account the increased amphotericin B resistance and significantly diminished susceptibility of mutant cells to lyticase digestion, the cell wall structure and/or composition may probably be responsible for the observed changes in the susceptibility of mutants to the antifungal compounds used.