Transient Phenomena in Continuous Culture*

The technique of continuous culture has become an important tool only for studies of microbial physiology, but also for use in the production of microbial products such as single cell protein, enzymes, and organic acids. This chapter aims to examine some of the work that has been done on transient systems in continuous culture. Initial attention will be paid to a description of the response of microbial systems to changes in the environment. A method to induce transients in continuous culture is through the pulse addition of the limiting nutrient to temporarily remove the nutrient limitation. A step increase in the limiting substrate concentration in the feed medium causes a transient increase in specific growth rate, after which it returns to the original specific growth rate, but at a new and higher cell density.