Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

First Advisor

Donal F. Day


The parameters of bioconversion of limonene to $\alpha$-terpineol by Penicillium digitatum were determined. This bioconversion was carried out stereo-specifically and selectively by this fungus. (R)-(+)-limonene was selectively converted to (R)-(+)-$\alpha$-terpineol by mycelia of this fungus during early growth phase. Immobilization of the fungal mycelia for use in continuous production of this product was possible. Aeration was critical to this bioconversion. The optimum aeration was about 1.6 mg/L for growing cells and immobilized cells. Substrate inhibition of the bioconversion was not observed when the substrate concentration was below 4% (v/v). End product inhibition was observed. The $\rm Ki\sb{app}$ was 12.08 mM. The optimum temperature was $28\sp\circ$C. Optimum pH was 4.5 for resting cells and 7.0 for immobilized cells. The optimum substrate contact time for this bioconversion was 1 to 2 days and 3 to 4 days for free cells and immobilized cells respectively. Several organic solvents and detergents were found to increase bioconversion yield for free and immobilized fungal cells. The half-life of immobilized mycelia was dependent on the amount of aeration. At the 0.3 SLPM aeration, the half-life of immobilized fungal mycelia was about 7 days.