Oscillatory behavior of population density in continuous culture of genetic-engineered Bacillus stearothermophilus

An oscillatory behavior in population density was observed when a transformant of Bacillus stearothermophilus carrying a rocombinant plasmid pZAM26 was cultivated continuously in a well-stirred reactor vessel at a fixed dilution rato. Among the transformant cells that were subjected to the continuous culture, the fraction of cells harboring p2AM26 was found to be as high as 0.98-1.00 despite the emergence of the oscillation. Cells whose plasmids underwent rearrangement of DMA in terms of structural change could not be found throughout. With reference to this observation, the dynamics of the genetic-engineered bacterium was analyzed within the category of both the linearized stability principle and the bifurcation theory. It was concluded that Hopf bifurcation was most probable to account for the experimental oscillation.