Bioconversion of (R)-(+)-limonene by P. digitatum (NRRL 1202)

Racemic limonene was enantio-selectively and enantio-specifically converted to (R)-(+)-α-terpineol by Penicillium digitatum mycelia. Bioconversion only occurred during the early to mid-log phase of growth. This pattern held true when different age inocula were used. Bioconversion activity increased more than 4-fold after substrate induction. Aeration was critical to this bioconversion. The optimum oxygen requirement was 1.6 mg/litre. Up to 4% (v/v) limonene did not inhibit the bioconversion. α- Terpineol inhibition was seen at concentrations greater than 25.9 mM. The optimum conversion temperature was 28°C, and the optimum pH was 4.5. The highest concentration of product was formed with a contact time of between 1 and 2 days.