When cells of growing exponentially on -glucose as sole carbon source were washed and transferred to buffered yeast nitrogen base containing 100 mM-acetate, they were unable to resume growth for several days whereas they adapted within a few hours to grow (slowly) on ethanol, and within 12 h to grow on pyruvate. After the cell transfer, oxygen consumption and ATP concentration decreased rapidly but recovered within a few hours on ethanol, more slowly on pyruvate, and only after 70 h on acetate. When the acetate culture had lost all detectable ATP, the viable cell titre slowly decreased until after 70 h enough cells had adapted to resume growth. At lower acetate concentrations (optimally 5 to 15 mM), ATP decreased less, and growth resumed within 1 d. After transfer from glucose medium to buffer plus a carbon source, cells sporulated equally well at ethanol concentrations from 20 to 150 mM and at pH 5.5 or 7.0; with dihydroxyacetone, another uncharged carbon source, sporulation was optimal at concentrations between 30 and 50 mM and about equal at pH 5.5 and 7.0. In contrast, after transfer from glucose medium to buffer plus acetate, cells sporulated at pH 5.5 optimally with 15 mM-acetate but not with 50 mM-acetate or more; at pH 7.0 sporulation showed a broader optimum of acetate concentration around 50 mM. The results indicated that in cells not adapted to gluconeogenesis, high concentrations of neutral acetic acid molecules caused complete consumption of intracellular ATP; consequently the cells could not adapt to gluconeogenesis for a long time.


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