Paenibacillus dendritiformis Bacterial Colony Growth Depends on Surfactant but not on Bacterial Motion

Author :Avraham Be'er, Rachel S. Smith, H. P. Zhang, E.-L. Florin, Shelley M. Payne, and Harry L. Swinney
Publication :Journal of Bacteriology
Volume :191
Number :18
Pages :5758'5764
Year :2009

Most research on growing bacterial colonies on agar plates has concerned the effect of genetic or
morphotype variation. Some studies have indicated that there is a correlation between microscopic
bacterial motion and macroscopic colonial expansion, especially for swarming strains, but no measurements
have been obtained for a single strain to relate the microscopic scale to the macroscopic scale. We
examined here a single strain (Paenibacillus dendritiformis type T; tip splitting) to determine both the
macroscopic growth of colonies and the microscopic bacterial motion within the colonies. Our multiscale
measurements for a variety of growth conditions revealed that motion on the microscopic scale and
colonial growth are largely independent. Instead, the growth of the colony is strongly affected by the
availability of a surfactant that reduces surface tension.