1981 Volume 34 Issue 9 Pages 1081-1089
A novel β-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 physicochemical data. The IR and NMR spectra suggested that iSZ has a β-lactam ring, methoxyl and sulfonate groups. On acid hydrolysis, it gave L-alanine and Dglutamic acid. iSZ is an epimeric isomer of sulfazecin. iSZ was weakly active against Grampositive and -negative bacteria, and was strongly active against mutants hypersensitive to β-lactam antibiotics.