Production of [14C]rubratoxin B.

[14C]rubratoxin B was produced by culturing Penicillium rubrum Stoll for 13 days at 22 degrees C in medium containing [14C]glucose. The most efficient incorporation of glucose into rubratoxin occurred when Raulin-Thom medium enriched with 2.5% malt extract was supplemented with 2.5% added glucose. The presence of 1.0 mCi of radioactivity in 50 ml of medium with 2.5% added glucose resulted in the production of 38 mg of labeled, chromatographically pure rubratoxin with a specific activity of 0.47 Ci/mole.