FIG 3.

Scanning electron microscopy of S. liquefaciens biofilms. Shown are representative scanning electron micrographs of bacterial biofilms formed on plastic surfaces at the liquid-air interface in LB medium. (a and a′) Strain no. 1 at 24°C; (b and b′) strain no. 1 at 37°C; (c and c′) strain no. 13 at 24°C; (d and d′) strain no. 13 at 37°C; (e and e′) strain no. 7 at 24°C; (f and f′) strain no. 7 at 37°C. Arrows in panels c, e, and f indicate the air-liquid interface. Arrows in panels c′ and d′ indicate putative pili. Note that pili were not limited to the polar region (as a polar flagellum would be). Panel b′ is a detail of strain no. 1 showing three distinct morphotypes in a biofilm: normal cells (long arrows), elongated cells (short arrows), and ghost cells (asterisks). Arrowheads indicate elongated cells that appear to intersect. Panel e′ is a detail of the boxed area in panel e. Magnifications: ×1,800 (a and b), ×10,000 (a′, b′, and f′), ×1,000 (c), ×15,000 (c′), ×200 (d and e), ×20,000 (d′), ×3,500 (e′), and ×2,000 (f). Bars: 25 μm (a, b, and f), 5 μm (a′, b′, and f′), 50 μm (c), 2.5 μm (c′ and d′), 250 μm (d and e), and 15 μm (e′).