SYSTEMS UTILIZING OXYGENATED LEGHEMOGLOBIN AND MYOGLOBIN AS SOURCES OF FREE DISSOLVED O2 AT LOW CONCENTRATIONS FOR EXPERIMENTS WITH BACTERIA

Oxygenated soybean leghemoglobin and sperm whale myoglobin have been used as sources of O2 for respiring bacteria in experiments with no gas phase. These O2-carrying hemoproteins provide dispersed free O2 at concentrations defined by the kinetic constants of their oxygenation and deoxygenation, and their optical absorption spectra indicate the average concentration of free O2. They can thus be used to study relationships between concentrations of free O2, rates of respiration, and other metabolic processes in bacteria suspended in solutions of them. Three types of apparatus are described and examples of studies of respiration and nitrogen fixation by Rhizobium spp. are given. © 1979.