Some Quantitative Relationships in Bacterial Population Cycles

Abstract

Although bacterial population cycles have been rather extensively studied qualitatively, accurate quantitative interpretation of certain aspects of the growth phases is wanting. This is due chiefly to the lack of comparable data on various organisms obtained under controlled, reproducible environmental conditions. The present investigation was undertaken to define more precisely the reproductive cycles of some of the common saprophytes under controlled, comparable conditions. In particular, the effect of temperature on reproduction was studied. From these growth curves, certain generalized quantitative relationships are derived. No attempt is made here to review as a whole the literature on growth curves; this has been done adequately by Henrici (1928), Buchanan and Fulmer (1928, 1930), and Rahn (1932). A complete review is also given in the author's original thesis (Jennison, 1932). METHODS Broadly, the experiments involved growing severalorganisms in broth at various temperatures under accurately controlled 1 Portion of a thesis submitted to the Graduate School of the Massachusetts Institute of Technology, May, 1932, in partial fulfillment of the requirements for the Degree of Doctor of Philosophy. ' Contribution No.

Evolutionary rescue at different rates of environmental change is affected by trade‐offs between short‐term performance and long‐term survival

“…Serratia marcescens spp. DB11 belongs to the family of Enterobacteriaceae , and it is a gram‐negative, nonsporulating opportunistic pathogen and has a generation time of 26 min at 32°C (Jennison, 1935). It generally lives in temperatures between 5 to 40°C, and it is between 0.5–0.8 by 0.9–2.0 µm in size.…”

The Relations Between Plate Counts and Direct Microscopic Counts of Escherichia coli During the Logarithmic Growth Period

“…The bacterial counts, when plotted against time on semi-log paper, gave typical sigmoid growth curves (Jennison, 1935). Because of the fact that during the earliest part of the logarithmic growth period the density of cells was too low to make accurate direct counts, the data for comparison here include the latter half of this phase and one subsequent two-hour growth interval at each temperature in tables 2 and 3.…”