PHENOTYPIC, GENOTYPIC, AND CHEMICAL CHANGES IN STARVING POPULATIONS OFAEROBACTER AEROGENES

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Abstract
Harrison, Arthur P., Jr.(Vanderbilt University, Nashville, Tenn.)and Felix R. Lawrence. Phenotypic, genotypic, and chemical changes in starving populations ofAerobacter aerogenes. J. Bacteriol.85:742–750. 1963.—Cells harvested from postlogarithmic (maximal stationary phase)Aerobacter aerogenescultures and starved in dilute sodium phosphate at 40 C remained viable for many hours. On the other hand, most cells from logarithmic-phase cultures succumbed, although a relatively small number remained viable. This viable segment of the original population thus responded like cells from postlog-phase cultures and, in fact, had properties in common with them. The residual segment was comprised of cells of two kinds. The first were mutants; when cultivated, harvested during log-phase growth, and again starved, they were resistant. The second were wild-type; they responded exactly as before. During starvation, the mutant is at an advantage because it has the ability to convert from susceptible log-phase physiology to resistant postlog-phase physiology more rapidly than can wild-type. The mutant differs from wild-type in yet other ways. It is smaller in size, slower in growth rate, lower in ribonucleic acid (RNA)-deoxyribonucleic acid ratio, greater in light-scattering ability, and, during the first 4 hr of starvation, it loses a higher proportion of its RNA. Selection of mutants of low growth rate between periods of active clonal growth indicates that evolutionary advantage may not necessarily be with the fast-growing members of the clone.