Spore production and viability of ECM mutants. Total spores from 5 × 107 cells incubated for 5 days were enumerated microscopically (solid bars). Viable spores were determined by plating spores on CYE agar (hatched bars). Error bars indicate the standard deviation. The top-left area of each panel displays the genetic background containing each mutation: WT, wild type, DK1622; pilA, ΔpilA, DK10410; fibA, ΔfibA, LS2429.