Patterns of growth and gliding motility of Simonsiella and Alysiella

Forty six strains of Simonsiella and two strains of Alysiella, large filamentous, gliding bacteria from the oral cavities of warm-blooded animals, were grown under various environmental conditions in order to study aspects of the taxonomy of these organisms. Differences in growth with changes in temperature, pH, and NaCl and synthetic sea water salts concentrations segregated the strains into several individual groups which correlated with the isolation of the strains from dogs, sheep or humans. These findings add to the information derived from studies on the cellular morphology and on the biochemistry and physiology (Kuhn et al., 1974; Pangborn et al., 1973 and 1974; Nyby, 1974; Gregory, 1975), on the fatty acid profiles (Jenkins, 1976), and on the mole percent G+C content (Kuhn et al., 1974). Microscopic features of gliding motility and growth patterns of Simonsiellaceae are recorded for the first time. Growth on agar viewed microscopically revealed that a small fraction of Simonsiellaceae strains glided, whereas other strains displayed types of colony morphology that ranged from entire-edged to pronounced filamentous growth. Gliding motility rates were found to range from 5 µm/min to 23.8 µm/min. Gliding motility was manifested by individual, frequently well-separated filaments rather than by “armies” of closely-associated cells as described by Stanier (1942a) for the cytophagas. Gliding motility appeared to occur as necessary to reach areas on the agar surface supplying fresh nutrients, and when these areas were reached gliding motility was arrested and secondary colony formation ensued. Gliding motility was frequently most pronounced in regions of heavy growth bordering unoccupied agar surfaces, suggesting that filaments glide in response to gradients of either decreasing waste metabolites or increasing fresh nutrients. The influence of other factors such as light, agar concentration and humid incubation are considered.