Regulation of the mctP promoter. Specific fluorescence (fluorescence [excitation at 485 nm; emission at 510 nm] optical density at 595 nm−1) was used as a measure of expression of the mctP promoter-green fluorescent protein fusion in different strains grown in AMS minimal medium with 10 mM glucose and 10 mM ammonium chloride (A) or in RU1601 (3841 pRU923) grown on different carbon and nitrogen sources (B). Data shown are the means of at least three independent experiments. Abbreviations: G, 10 mM glucose; N, 10 mM ammonium chloride; S, 10 mM succinate; A, 20 mM alanine; P, 20 mM pyruvate; L, 20 mM lactate.