Heat sterilization using a novel autoclave, Stirclave(R), was studied as compared with that of a conventional autoclave. The outline of the apparatus is the same as a conventional autoclave except for a turntable used in rotation, which is activated by a roller connected to a motor. From temperature measurements, it was found that temperature at the bottom of the vessel was significantly lower compared with that at the top of the vessel in the non-rotational mode, while both temperature profiles were nearly the same in the rotational mode. When ii of a medium used in antibiotics production, which also contained 10(5)/ml of spores of Bacillus subtilis as a contaminant, was sterilized for 20 min in both modes and the medium was used for cultivation of Streptomyces fradiae, the complete sterilization and antibiotic production were observed in the medium sterilized by the rotational mode, while the growth of B. subtilis and no production of antibiotics were observed in non-rotational mode.