Effect of Mutant of Bacillus subtilis on the Specific Transport of Aconitase and Dicarboxylic Acid

Abstract

AMONG mutants obtained by heating dry spores of B. subtilis¹ and detected by their loss of the ability to grow on glycerol–ammonium medium, one mutant (Marburg C4–4) behaves in an unexpected way. As with other mutants or other strains of the same species, growth occurs with the addition of glutamate². The glutamate can be replaced by arginine, proline and ornithine, as would be expected from the occurrence in Bacilli of an inducible enzymatic decomposition of these amino-acids into glutamate^2,3. However, in contrast to most cases, aspartate does not support growth in spite of an active asparto-glutamic transaminase. In addition, the oxidation of the dicarboxylic acids and the citric acid present in the parent strain (Marburg C4) vanishes strikingly in the mutant, in both cases after a growth in the same medium (glycerol, glutamate) (Table 1). Contrasting with the lack of oxidation by the resting cells, lysozyme lysates of concentrated suspensions of the mutant as well as parent oxidize the dicarboxylic acids and isocitric acid at the same speed. The only difference is the incapacity of the mutant lysate to oxidize citrate and cis-aconitate (Table 2). A specific test⁴ shows that both activities of aconitase (hydration and dehydration) are absent in the mutant; isocitric dehydrogenase remains present (Table 3).