SELECTION OF THERMOSTABLE SERRATIA MARCESCENS FROM LOGARITHMIC-PHASE CULTURES AS A MEANS FOR INDUCING SYNCHRONOUS GROWTH

Abstract

HESS, GEORGE E. (U. S. Army Chemical Corps, Fort Detrick, Maryland) AND MILTON SHON. Selection of thermostable Serratia marcescens from logarithmic-phase cultures as a means for inducing synchronous growth. J. Bacteriol. 83:781-784. 1962.-A relatively thermostable, apparently nonmultiplying, population of Serratia marcescens was found in cultures in the exponential phase of growth. Thermal treatment of the whole culture resulted in the death of the multiplying cell fraction, although the nonmultiplying fraction remained viable. Subcultivation of the thermally treated suspensions yielded cultures in which most of the viable organisms multiplied synchronously for at least two generations. Synchronous growth of organisms can be induced through various techniques (Campbell, 1957) which utilize the response of the organism to variables such as illumination level (von Denffer, 1958), incubation temperature (Lark and

Rhythmic Response of Serratia marcescens to Elevated Temperature

“…the absence of a colony is not proof that death had occurred. Harrison and Lawrence (1963) and Hess and Shon (1962) attributed periods of enhanced viability, or of "tailing" of survivor curves as a result of stress, to the growth of selected mutants or variants. My data show instances of fluctuation of viable numbers too rapid to be considered a result of cell replication during stress, and fluctuations during growth too repeatable (qualitatively) to be entirely random in nature.…”

Injury and Growth of Serratia marcescens Studied in a Thermal Gradient Incubator

“…Further, cells heated for 15 or 120 min grew faster, and over a wider temperature range, than did cells heated for 90 min; i.e., recuperation (Dimmick, 1965) had occurred after 90 min. Elevated temperatures either killed or injured a portion of the population capable of growing at lower temperatures or, as suggested by Hess and Shon (1962), a population capable of growing at elevated temperatures was activated by the heat treatment.…”

Rhythmic Response of Serratia marcescens to Elevated Temperature

“…The presence of a colony is proof of life; the absence of a colony is not proof that death had occurred. Harrison and Lawrence (1963) and Hess and Shon (1962) attributed periods of enhanced viability, or of "tailing" of survivor curves as a result of stress, to the growth of selected mutants or variants. My data show instances of fluctuation of viable numbers too rapid to be considered a result of cell replication during stress, and fluctuations during growth too repeatable (qualitatively) to be entirely random in nature.…”