Biotransformation of menthol by sporulated surface cultures of Penicillium sp. and study of the pathways involved
A simple and efficient method of carrying out biotransformation reactions on terpenoid compounds was developed. For these experiments, a sporulated surface culture of Penicillium sp. was inoculated on solid media in conical flasks. After a short incubation the spores germinated and a mycelia culture was formed. After a week the cultures had completely sporulated and a bioconversion reaction started. For this purpose, a known volume of menthol was added onto the sporulated surface of culture. After 7 days, a period during which transformation took place, menthol was extracted with Et2O three times. After evaporation the recognition by GC and GC/MS was followed. The main bioconverted products obtained from menthol by surface Penicillium sp. with the use of sporulated surface culture were α-pinene (18.0%), sabinene (11.6%), trans-p-menthan-1-ol (10.6%), p-menth-1-ene (5.8%), 1,8-cineole (6.4%) and limonene (3.2%). The pathways of biotransformation of menthol by Penicillium sp. to main products are also discussed.