RESUMEN
Erwinia herbicola CHS1065 produces antifungal compounds highly related to herbicolin A. In 11 Tn5 mutants that have lost the antifungal activity, the transposon insertion is located on a 170-kb plasmid present in CHS1065. This plasmid was designated pHER1065. When analyzing these antifungal mutants, it was found that the genes for the biosynthesis of the antifungal compounds were organized in at least two clusters on pHER1065. Upon insertion of the aphII gene of Tn5 and genes for plasmid mobilization in pHER1065, the plasmid could be stably introduced into Escherichia coli. All the E. coli exconjugants expressed an antifungal activity that was quantitatively and qualitatively comparable to the activity produced by E. herbicola CHS1065. Amino acid analysis and molecular weight determinations of the antifungal compound produced by CHS1065 were identical to those of herbicolin A.