ROLE OF SULFUR METABOLISM IN COPPER-RESISTANCE OF YEAST

Cells of a normal yeast strain and of its copper-resistant substrainwere more severely injured by copper treatment under sulfurdeficiency than under nitrogen or carbon deficiency. Even underthese starved conditions, the resistant substrain gave higherviable counts than the parent strain after the copper treatment.Several hours were needed for the sulfur-starved cells to recovertheir copper-resistance when resupplied with sulfur. The observed effect of the amount of sulfur supply on the cellyield was not contradictory to the idea that resistant cellsuse for their resistance mechanism a part of sulfur they absorb.Methionine made cells more sensitive to copper, and this effectwas antagonized by ethionine to some extent. The importance of sulfur metabolism in copper resistance isdiscussed. ¹This work was supported by a Grant in Aid for Fundamental ScientificResearch, Ministry of Education, Japan.²Present address: Konan University, Kobe, Japan. (Received October 8, 1959; )