GLUTAMATE METABOLISM IN BRUCELLA ABORTUS STRAINS OF LOW AND HIGH VIRULENCE

Abstract

Brucella abortus strains of low virulence oxidize glutamate at a high rate, whereas strains of high virulence oxidize glutamate at a relatively low rate. Results indicated that this observation was not related to differences in pathway of glutamate oxidation or to differences in total enzyme activity. Permeability studies showed that the maximal rates of glutamate accumulation were 2.8 Amoles per 2 min per g (wet wt) for a strain of high virulence and 6.2 ,moles per 2 min per g for a strain of low virulence, but equal intracellular steady-state concentrations were attained by both types of strains. Evidence

Biochemical Properties of Virulent and Avirulent Strains of Brucellae*

“…N (endogenous subtracted).and Housewright, 1952). Our result(Dasinger, 1960) with a virulent strain of B. aborfus (2308) indicates an identical pathway to that found by Marr et d.(1953) for a strain of low virulence.…”

“…On reducing the quantity of cells in the Warburg vessels (Grogan, 1957) so that oxygen starva-tion was not a factor, we found no depression of respiration rates of strains of low or high virulence. The effect of low oxygen tension on the respiration of B. ubmtus was further studied with the polarograph using a dropping mercury electrode (Dasinger, 1960). I t was shown (FIGURE 1) that the rate of change in oxygen concentration is not dected down to 0.05 ppm of oxygen.…”

“…This pathway of oxidation of glutamate was proposed from oxidative studies with postulated intermediates, the effect of inhibitors, products of oxidation, and the ratio of oxygen uptake to glutamate disappearance (Marr et al, 1953). A tricarboxylic acid cycle is also operative in B. aborhs, strain 19 (Altenbern (Dasinger, 1960). B. aborlus, strain 11, has a very low virulence for the guinea pig, because lo7 cells do not produce progressive infection, while B .…”