We observed direct binding of C. difficile Spo0A to the promoter region of sigH (Fig. 3A) . This gene encodes the key sigma factor for the transition phase, and regulates processes outside sporulation as well [37] . Moreover, we found significant levels of Spo0A from early stationary phase on ( Fig. 1B and unpublished observations) , indicating the regulatory actions of Spo0A need not be limited to stationary phase in C. difficile. In line with this idea, we found a potential regulatory link between Spo0A and two genes that to our knowledge are not related to the sporulation process, the lipoate ligase lplA and the aliphatic sulfonates transporter ssuA (Fig. 3A) . The presence of a putative Spo0A binding site upstream of these genes, as well as the spacing compared to the start codon, is conserved in the problematic Stoke-Mandeville strain (R20291), a member of PCR ribotype 27. This could indicate that these aspects of regulation by Spo0A are conserved in multiple strains of C. difficile.