Reduction of Ketopantoyl Lactone to D-(—)-Pantoyl Lactone by Microorganisms

The ability to reduce ketopantoyl lactone added to the culture medium to pantoyl lactone was surveyed in a variety of microorganisms. Many of the microorganisms including molds, yeasts, bacteria, actinomycetes and basidiomycetes exhibited this ability. The ratios of D-(—)- and L-(+)-isomers of the yielded pantoyl lactone, however, showed no relation to the genera or sources of strains. Among them, Rhodotorula minuta IFO 0920, Candida parapsilosis IFO 0708 and Aspergillus niger IFO 4415 were found to convert ketopantoyl lactone (45mg/ml) completely and almost specifically to D-(—)-pantoyl lactone. The main enzyme catalyzing this asymmetric reduction was suggested to be ketopantoyl lactone reductase (EC 1.1.1.168).