Spo0A positively regulates glucose fermentation pathways and butyrate production in C. difficile. a) Proposed biochemical pathway for glucose uptake and fermentation leading to the production of butyrate. Genes in red are downregulated in the C. difficile spo0A mutant and genes in green are upregulated in the C. difficile spo0A mutant. Genes in black are not impacted by the spo0A mutation. b) Levels of butyrate from supernatants of C. difficile strains during exponential growth. Analysis was performed in triplicate and levels compared using a Student’s T test; **, P = 0.0005; *, P = 0.6.