Isosulfazecin, a new beta-lactam antibiotic, produced by an acidophilic pseudomonad. Fermentation, isolation and characterization.

A novel beta-lactam antibiotic, isosulfazecin (iSZ), was found to be produced by an acidophilic pseudomonad, Pseudomonas mesoacidophila sp. nov. iSZ was produced in parallel with bacterial growth in nutrient broth containing glycerol and sodium thiosulfate under aerated conditions. iSZ was isolated by chromatography on activated charcoal and anion-exchangers and crystallized from 70% aqueous methanol. The molecular formula was determined to be C12H20N4O9S from physiochemical data. The IR and NMR spectra suggested that iSZ has a beta-lactam ring, methoxyl and sulfonate groups. On acid hydrolysis, it gave L-alanine and D-glutamic acid. iSZ is an epimeric isomer of sulfazecin. iSZ was weakly active against Gram-positive and -negative bacteria, and was strongly active against mutants hypersensitive to beta-lactam antibiotics.