Epigrisorixin, a new polyether carboxylic antibiotic.

addition of methyl oleate (1%) to the original fermentation culture increased the antibiotic titer3). Under these conditions, three nigericin-type antibiotics were isolated, grisorixin (1) (unpublished data), abierixin3) and epinigericin4) (3). The comparative biological activity of the two epimeric antibiotics, nigericin and epinigericin on a protist Tetrahymena pyriformis GL5) and Bacillus cereus^ showed that epinigericin was less toxic