Translocation of Motile Cells of the Gliding Bacterium Cytophaga johnsonae Depends on a Surface Component that May Be Modified by Sugars

Abstract

SUMMARY: Twenty-three sugars and sugar derivatives prevent the spread of colonies of the gliding bacterium Cytophaga johnsonae on 1–5% agar gels. Concentrations of sugars that inhibit colony spread have no inhibitory effect on motility or growth of cells. Observations of patterns of colony spread on plates with pre-established concentration gradients of sugars indicate that cells of C. johnsonae do not exhibit a chemotactic response to compounds that inhibit their spread. Inhibitory compounds were placed into three groups based on their relative effectiveness as inhibitors. Both metabolizable and non-metabolizable sugars served as inhibitors, it was not necessary for a sugar to be transported into the cell to inhibit, and the effectiveness of a sugar as an inhibitor did not correlate with its ability to support growth. The inorganic ions Mg2 °, Ca2 + and SO|∼ also inhibit colony spread on 1–5% agar gels. All the evidence taken together suggests that inhibitors of spread produce their effects by modifying the properties of a surface slime. The observations reported here help to give an experimental definition to two components of the gliding motility system of C. johnsonae: the motility ‘machinery* that is responsible for an actively moving cell surface and is not affected by the presence of sugars, and an extracellular component which is sensitive to sugars and which is required for translocation of cells with moving surfaces.