BIOSYNTHETIC STUDY ON THE POLYETHER CARBOXYLIC ANTIBIOTIC, NIGERICIN - PRODUCTION AND BIOHYDROXYLATION OF GRISORIXIN BY NIGERICIN-PRODUCINGSTREPTOMYCES-HYGROSCOPICUS NRRL-B-1865

With addition of methyl oleate, the increased yield of antibiotic prod uction by nigericin-producing Streptomyces hygroscopicus NRRL B-1865 a lso resulted in the isolation of three additional polyether antibiotic s. Two of these are abierixin and epinigericin, as new antibiotics. Th e third antibiotic is grisorixin. The production of both abierixin (op ened ring A and 30-CH2OH) and grisorixin (ring A and 30-CH3) poses the problem of the identity of the last pathway precursor of the major me tabolite, nigericin (ring A and 30-CH2OH). Transformation experiments of abierixin by S. hygroscopicus gave negative results. Hydroxylation of grisorixin to nigericin by S. hygroscopicus represents the final st ep in nigericin biosynthesis.