Yeast Killer Factor-induced Turbidity Changes in Cells and Sphaeroplasts of a Sensitive Strain

Summary: When a culture of a sensitive yeast strain is treated with yeast killer-protein, there is an increase in turbidity. This killer protein-induced turbidity increase coincides with the loss of cellular ATP, and appears to be caused by increased light scattering owing to a reduction in volume of the treated yeast cells. Sphaeroplasts prepared from sensitive cells were also sensitive to killer protein, and a culture showed a large increase in turbidity when treated with killer protein. The increase in turbidity of sphaeroplasts was not accounted for by a change in volume, but did correlate with killer protein-induced alterations in membrane permeability, and is consistent with a killer protein-induced alteration in light scattering of the yeast cell membrane.