Fig. 2

Nitrogen source utilization microarray. The lists include all positive simple (a) and di- and tri-peptide (b) nitrogen source phenotypes (green) for C. sordellii and C. difficile (lanes 1 and 2, respectively). Negative phenotypes are red (c). The C. sordellii : C. difficile ratio of growth enhancement for each dipeptide nitrogen source phenotype is grouped by amino acid (circles; average – white squares). Gray circles indicate the position 1 amino acid (position 1 average – green squares) while white circles indicate the position 2 amino acid. Amino acids are further grouped (I-V) by their expected pathway to nitrogen metabolism (d)