FIG 1.

Gliding of wild-type and ΔgldN mutant cells on agar. Cells were grown in TYES at 18°C for 24 h to late exponential phase (OD of approximately 1.3). Ten microliters of cultures were spotted on TYES solidified with agar (10 g/liter) and observed for motility using an Olympus BH-2 phase-contrast microscope. Results for wild-type (WT) F. psychrophilum, the ΔgldN mutant, and the ΔgldN mutant complemented with wild-type gldN on pBFp4 are shown. In each case, a series of images were taken using a Photometrics Cool-SNAP_cf² camera. Individual frames were colored from red (time zero) to yellow, green, cyan, and finally blue (132 s) and integrated into one image, resulting in “rainbow traces” of gliding cells. The top row shows the first frame for each strain, and the bottom row shows the corresponding 132-s rainbow trace. White cells in the bottom panel correspond to cells that exhibited little if any net movement. Scale bar at lower right applies to all panels. The rainbow traces correspond to the sequences in Movie S1 in the supplemental material.