Spore properties.

(A) Adhesion of the mutant and wild-type spores to glass tubes. The spores purified from strain 168 (WT), SPRAd (sprA), YODUd (yodU), SPRAc (sprA spsM⁺), and YODUc (yodU spsM⁺) were resuspended in water and the final OD₆₀₀ was adjusted to 15. Each 30 µl of spore resuspension was added to a Pyrex tube (13×100 mm, Corning) and vortexed gently for 30 s. After removing the spore resuspensions, the glass tubes were briefly dried and images were acquired. (B) Adhesion of the mutant and wild-type spores to polypropylene tubes. Adhesion (%) was determined by 10 successive binding reactions of the spores to the tubes. Error bars indicate ± standard deviations based on three independent experiments. (C) The polysaccharide layer facilitates spore dispersal through water flow. Overnight cultures of B. subtilis cells grown in LB medium were spotted onto DSM-agar plates. The plates were incubated at 37°C for 1 week. Each colony was confirmed as containing>95% free spores using phase-contrast microscopy. The images show the spore colonies on the DSM plates before (upper panels) and after rinsing with 1 ml of DDW (lower panels). The wild-type spores on the plates were dispersed by water, whereas the mutant spores stuck to the plates.