| Research Abstract |
Bacteria form a colony with characteristic morphology and internal structure by successive cell multiplication and swarming on a solid medium. By analyzing processes of such morphogenic growth, we found that bacteria are organism exerting mass behavior.
In the present study, such bacterial mass behavior was traced by CCD camera and video-recorded for precise analyzes. Mutants of Serratia marcescens were collected by transposon mutagenesis for mutational analyzes of fundamental protocols in mass behavior, such as cooperated translocation, mutual recognition.
1.In a spreading growth of flagellum-less S.marcescens on a lowagar medium, production of biosurfactant "serrawettin" was shown to be critical. Roles of biosurfactants in translocating mass behavior of bacteria were indicated by various mutational analyzes.
2.Proteus mirabilis exhibited specific swarming behavior in response to the presence of a specific amino acid. Such behavior was a solid medium-specific response of a P.mirabilis population.
P.mirabilis point-inoculated onto the central surface of a semi-solid medium, promptly spread on the whole surface. These bacteria residing on the surface, therafter, entered into the special phase and demonstrated characteristic spatio-temporal pattern, e.g., Moire-like dynamic pattern, multifocal aggregation of swarming bacteria, and translocation and fusion of such aggregates.
From findings described above, it is evident that bacteria on a surface environment are living in cooperation. Experimental analysis of these characteristic behavior will uncover bacterial real mode of life in nature.
3.Growing interface of a Bacillus subtilis colony was examined for self-affinity, as a typical example of random pattern growth. By quantitative analysis of behavioral data, the values of alpha (roughness exponent) =0.5 and 0.78 depending on microscopic mode of interface growth were obtained.
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