FIG 2 .

Medium neutralization induced by growth on carboxylic acids does not generate ammonia. The wild-type SC5314 strain was spotted onto solid YNB medium with the indicated compound as the sole carbon source and allowed to develop into a colony at 37°C. Directly apposed to the colony, a small reservoir was affixed to the lid of the petri dish and filled with 10% citric acid. At the indicated times, a sample of the liquid in the acid trap was removed and assayed for nitrogen content using Greiss reagent; the results are expressed as parts per million (ppm). CAA, Casamino Acids; Glut, glutamate; Ser; serine; Pyr, pyruvate; αKG, α-ketoglutarate; Ace, acetate; Lac, lactate. Error bars show standard deviations.