Fosfonochlorin, a new antibiotic with spheroplast forming activity.

A new antibiotic, fosfonochlorin, was found in the culture filtrate of four strains of fungi freshly isolated from soil samples. These strains were identified as Fusarium avenaceum, Fusarium oxysporum, Fusarium tricinctum and Talaromyces flavus. Fosfonochlorin was a low molecular weight antibiotic (MW 158), soluble in water and methanol, but insoluble in acetone, ethyl acetate and chloroform. It was named after its possession of phosphorus and chlorine atoms, each one molar in its structure. The structure was determined as chloroacetylphosphonic acid mainly by the 1H NMR and mass spectrometric analyses. It was moderately active against some species of Gram-negative bacteria and its synergistic effect with glucose-6-phosphate was observed on Staphylococcus aureus and Escherichia coli. Spheroplast formation of the susceptible organisms with this antibiotic suggested that it might inhibit their cell wall synthesis.