J. Phys. Soc. Jpn. 58 (1989) pp. 3875-3878 |Next Article| |Table of Contents|
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Fractal Growth of Bacillus subtilis on Agar Plates
Department of Microbiology, Tokyo Metropolitan Research Laboratory of Public Health
1Department of Physics, Chuo University
(Received August 31, 1989)
Bacteria have been shown to grow with various morphologies under different conditions on agar plates. A Bacillus subtilis strain was inoculated on the plate surface and incubated at 35°C. Colonies grew two-dimensionally with random branches, similar to clusters of the diffusion-limited aggregation (DLA) model. The colony patterns were analyzed and found to be self-similar with a fractal dimension of 1.716±0.008, in excellent agreement with the expected value of the DLA model. Interior branches were observed to stop growing in spite of their open neighborhood during the incubation period, implying the existence of a screening effect. These results clearly suggest that the colony pattern of the organism was formed through the DLA process. Moreover, the colonies were found to grow radially with almost regular branches on agar plates with moist surfaces, reminiscent of “dense radial” morphology.
©1989 The Physical Society of Japan
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