Abstract
Like sporidesmin, gliotoxin catalyzes the decomposition of azide in the presence of iodine, and this catalysis can be used for its estimation. The presence of respiring cells of Bacillus subtilis does not interfere with the estimation. Thus it was possible to show that the concentration of gliotoxin decreased when solutions of the antibiotic were incubated with respiring cells. The rate of the decomposition was independent of the gliotoxin concentration in the range 2–25 μg/ml, but was dependent on the number of cells, the pH, and the available nitrogen in the suspending medium. Loss of gliotoxin was most rapid at pH 5.5 and continued when the supernatant was reincubated after centrifugal removal of the cells. No loss of gliotoxin occurred when solutions were incubated in the absence of cells at pH 5.5. By contrast, chemical degradation at pH 8.0 was inhibited in the presence of cells. These results are consistent with the hypothesis that B. subtilis secretes an enzyme which degrades the disulfide group in gliotoxin.

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