METABOLISM AND POPULATION CHANGES IN BRUCELLA ABORTUS II

Abstract

Changes in relative proportions of smooth and nonsmooth type cells in originally smooth cultures of B. abortus strain 19 in a liquid defined medium are suppressed by the addition of hydrogen acceptors such as nitrate ion, methylene blue, and resazurin. Potassium nitrate in a concentration of 0.07% stimulates the growth of smooth type cells more than rough type cells. Incubation of smooth cultures under reduced air pressure greatly accelerates population changes. Under reduced pressure of air, rough types grow more rapidly than smooth types. Increases in the size of the smooth inoculum increase the rate and extent of population changes. The rough type cells, which constitute the majority of the viable population after prolonged incubation of originally smooth cultures, possess a greater affinity for sodium azide than the smooth parent cells. The implications of these results with regard to the probable causative mechanism of population changes are discussed.