A yeast lysis mutant: potential biotechnological applications

The conditional yeast lysis mutant cly8 was studied for potential biotechnological applications. The strain stops to grow immediately after a shift to elevated temperatures ( > 30°C). Cell viability (colony forming capacity) decreases at 37°C at a rate depending on the composition of the medium. However, at the elevated temperature cells still consume glucose and incorporate [ 14C]leucine into cell material. With decreasing viability the mutant cells become leaky for small, predominantly cytoplasmic components such as leucine or uridine but not for vacuolar storage products like arginine. No trichloroacetic acid-precipitable material could be detected in the medium after the shift to the elevated temperature indicating that leakiness was restricted to low molecular weight compounds. On acetate medium mutant cells became permeable only after prolonged incubation at 37°C but could be used for the oxidation of exogenous NADH. In comparison to the wild type the mutant also produced more glycerol. When the mutant cells were immobilized, glycerol production was in the same range at room temperature and at 28°C and could be maintained for several days.