FIG 5.

Growth of C. difficile on glucose in the absence of Stickland acceptors. A glucose-containing medium in which both glycine and alanine were omitted (Glc only) was used to grow C. difficile in the absence of all amino acid Stickland acceptors. Glc-only medium was similar to Gly/Ala medium without glycine and alanine. OD₆₀₀ (* and □) and concentrations (mM) of glucose (Glc), glycine (Gly), alanine (Ala), and ammonia (NH₃) are shown. Gly/Ala cultures were used to inoculate the Glc-only tubes, accounting for the small amounts of glycine and alanine present initially.