ATTACHMENT AND GROWTH OF BACTERIA ON SURFACES OF CONTINUOUS-CULTURE VESSELS.

Don H. Larsen (Brigham Young University, Provo, Utah), and R. L. Dimmick. Attachment and growth of bacteria on surfaces of continuous-culture vessels. J. Bacteriol. 88:1380-1387. 1964.-Initial attempts to induce synchrony in a continuous culture of Serratia marcescens by alternating growth temperatures produced fluctuations in the population of a magnitude and at a density higher than predicted by theory. Without temperature change, the density in the 14-ml volume changed with dilution rate, but the total output of cells per hour remained constant, even at dilution rates greater than critical. When glass wool was added to the culture vessel, the total output per hour increased 30-fold. Nonlethal ultrasonic agitation applied to the vessel reduced the population density in continuous culture under both a static and a cyclic temperature program. The decrease in population density, when the washout rate was momentarily increased about tenfold, was less than theoretically predicted, and the subsequent rapid rise, when flow was terminated, indicated the presence of a reservoir of cells on the walls of the vessel continually discharging their progeny into the medium. Several genera were examined in the latter manner; it is estimated that in some cases as many as 90% (S. marcescens, Escherichia coli), and in others (Bacillus spp.) possibly none, of the cells in suspension arose from wall inhabitants. Growth of bacteria on the walls of continuous-culture vessels can significantly influence the population density and, hence, the kinetics of continuous growth.