FIG 3.

(A to E) The ΔclpYQ deletion mutant formed more robust biofilms while impaired for swarming motility and cell separation. (A) A schematic drawing of the presumptive operon of xerC-clpY-clpQ-codY in B. cereus. The transposon insertion site within the clpY gene in BC42 is indicated by the triangle. (B and C) Pellicle (B) and colony (C) biofilms formed by wild-type AR156 and the clpYQ in-frame deletion mutant (FY178), and the clpYQ complementation strain (YY250) in LBGM. Scale bars, 5 mm (B) and 2 mm (C). (D) Swarming motility of AR156 and FY178 on LB plates solidified with 0.5% agar. Plates were incubated at 30°C for 12 h before images were taken. Scale bars represent 1 cm. (E) Cells of AR156 and FY178 grown to late-exponential phase (OD₆₀₀, 1) and observed under bright-field microscopy. Scale bars, 10 μm. (F and G) Genes involved in purine biosynthesis are important for biofilm formation in B. cereus. (F) A schematic drawing of the putative purine biosynthesis gene cluster in B. cereus AR156. The transposon insertion sites within the purH (BC85) and purD (BC61) genes are indicated by triangles. (G) Pellicle biofilm formation in LBGM by AR156, the two transposon insertion mutants, BC61 (purD::Tn) and BC85 (ΔpurH::Tn), and the two complementation strains, YY251(purD::Tn, pGFP78-purDH) and YY252(ΔpurH::Tn, pGFP78-purDH). Scale bars, 5 mm.