Solitary modes of bacterial culture in a temperature gradient.
We study the behavior of a bacterial culture in a one-dimensional temperature gradient. The bacteria first accumulate near their natural temperature due to thermotaxis. The maximum of the bacterial density profile then drifts to lower temperature with a velocity proportional to the initial concentration of bacteria (typical velocity 0.5 microm/sec). Above a critical concentration of 10(8) cells/cm(3), a new mode develops from the initial accumulation in the form of a sharp pulse moving at a faster velocity ( approximately 3.5 microm/sec). The time of development of this mode diverges as the concentration approaches its critical value. This mode is a result of a positive feedback mechanism provided by interbacterial communication. A theoretical model shows good agreement with the experimental results.
Salman
H
H
Center for Studies in Physics and Biology, The Rockefeller University, New York, New York 10021, USA.
Zilman
A
A
Loverdo
C
C
Jeffroy
M
M
Libchaber
A
A
D000596:Amino Acids / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D001703:Biophysics / Q000379:methods; D008954:Models, Biological; D008962:Models, Theoretical; D009154:Mutation; D016011:Normal Distribution; D013696:Temperature; D013997:Time Factors
D000596:Amino Acids