CHIRALITY OF THE GAMMA-LACTONES FORMED BY FUSARIUM-POAE INRA-45

A filamentous fungus, Fusarium poae INRA 45, was grown in two liquid C zapek-type media (a Czapek medium, and a yeast extract plus casaminoac ids-enriched Czapek medium). Eight gamma-lactones, i.e., gamma-penta-, gamma-octa-, gamma-nona-, gamma-deca-, and gamma-dodecalactone, (6Z)- gamma- and (6E)-gamma-dodecenolactones, and a di-unsaturated gamma-dod ecalactone, were tentatively, or conclusively, identified by capillary gas chromatography (GC) and coupled GC-MS, in the volatile fractions of the cultures. Kinetics of the formation of gamma-decalactone, (6Z)- gamma- and (6E)-gamma-dodecenolactones, (three major lactones), and ga mma-dodecalactone (a minor lactone) were quantitatively studied by com puterized GC integration. Variations of the (R/S) ratios of the lacton e enantiomers were quantitatively studied by computerized multidimensi onal gas chromatography (MDGC) integration. The levels of the lactones were superior in the enriched Czapek-type medium to those of the Czap ek medium, but the compositions of these media did not influence signi ficantly the (R/S) ratios of these lactones. Formation of the enantiom ers is discussed in terms of metabolism of potential precursors. (C) 1 993 Wiley-Liss, Inc.