Cells of a normal yeast strain and of its copper-resistant substrain were more severely injured by copper treatment under sulfur deficiency than under nitrogen or carbon deficiency. Even under these starved conditions, the resistant substrain gave higher viable counts than the parent strain after the copper treatment. Several hours were needed for the sulfur-starved cells to recover their copper-resistance when resupplied with sulfur.The observed effect of the amount of sulfur supply on the cell yield was not contradictory to the idea that resistant cells use for their resistance mechanism a part of sulfur they absorb. Methionine made cells more sensitive to copper, and this effect was antagonized by ethionine to some extent.The importance of sulfur metabolism in copper resistance is discussed.
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