Antibiotic Production by a Species of Cephalosporium

Summary: The antibacterial activity of a strain of a Cephalosporium sp. was found to be due to a number of antibiotics. One group of these, named Cephalosporins P, is soluble in organic solvents and active only against Gram-positive bacteria. The P antibiotic(s) is produced in good yield in deep culture in a medium comprising corn steep liquor and glucose at an initial pH of 6·3. A high aeration rate assisted by adequate stirring is essential. Submerged cultures 72 hr old form convenient inocula. Under optimum conditions with 2% (v/v) of such an inoculum the maximum titre is reached after 47–50 hr. at 24°, and thereafter falls.