Metabolic products of Aspergillus terreus. IX. Biosynthesis of butyrolactone derivatives isolated from strains IFO 8835 and 4100.

Two new derivatives of butyrolactone I were isolated from Aspergillus terreus IFO 4100, and the structures were determined. A metabolic pathway from phenylalanine to butyrolactone I was established by administration of potential intermediates to growing or resting cells of Aspergillus terreus IFO 8835 and by enzymatic studies. Three enzymes involved in the biosynthesis were identified.