FIG 6.

Filamentous cells are able to reach beyond the surface of a biofilm. (A) CB15 (holdfast⁺) cells grown in PYE overnight in a microfluidic device. The chamber was then flushed daily for several hours with diluted (1:10) PYE to wash away unattached cells and ensure a clear view of the biofilm. The upper panels show the colonization of a surface (see also Movie S2), and the lower panel shows filamentous cells extending from the biofilm after 4 days (see also Movie S3). A schematic sketch of the colonization is shown on the right. (B) Time-lapse microscopy of the filamentation of CB15 cells in spent medium with glucose in a microfluidic device to monitor the process of filament formation. Cells labeled with an asterisk originated from the first cell. Arrowheads indicate a division event during filamentation.