The Oxygen Uptake of Suspensions and Cultures of A Free-Living Bacterium

Abstract

ABSTRACT The oxygen uptake of pure cultures and suspensions of a free-living bacterial species has been measured at 26° C. At this temperature, liquid cultures reach the maximum stationary phase of growth about 96 hours after inoculation. The greatest total oxygen uptake was observed in samples taken from cultures 72 hours after inoculation, and the greatest uptake per cell at 48 hours after inoculation. The oxygen uptake in cultures which have reached the stationary state falls off rapidly, at each successive sampling, to a very low value. In suspensions deprived of nitrogen, and showing no growth, and in cultures in the stationary phase, oxygen uptake proceeds at a constant rate. In both suspensions and cultures, where active growth is taking place, the rate of oxygen uptake rises continuously; after a preliminary period of adjustment this rise is logarithmic. The rise in oxygen uptake in a growing suspension is proportionately greater than the rise in bacterial numbers. It is suggested that the oxygen uptake of a growing culture can be divided into two parts; “maintenance” respiration and “growth” respiration, and a technique is outlined for estimating the amount of oxygen uptake due to each factor.