Cometabolic isoterpinolene formation from isolimonene by denitrifying Alcaligenes defragrans

Alcaligenes defragrans strains denitrify on monoterpenes with an unsaturated hydrocarbon structure. A new cometabolic reaction, the formation of isoterpinolene from isolimonene, was detected in cultures that grew on a monoterpene. The biotransformation of isolimonene, a monocyclic monoterpene with a sp³-hybridized C1 atom of the menthane skeleton, contrasts with the complete mineralization of monoterpenes with a sp²-hybridized C1 atom. This selectivity indicates a demand for a sp²-hybridized C1 atom as structural property for monoterpenes that can be oxidized by A. defragrans.