Stenotrophomonas maltophilia: A Gram-Negative Bacterium Useful for Transformations of Flavanone and Chalcone.

A group of flavones, isoflavones, flavanones, and chalcones was subjected to small-scale biotransformation studies with the Gram-negative Stenotrophomonas maltophilia KB2 strain in order to evaluate the capability of this strain to transform flavonoid compounds and to investigate the relationship between compound structure and transformation type. The tested strain transformed flavanones and chalcones. The main type of transformation of compounds with a flavanone moiety was central heterocyclic C ring cleavage, leading to chalcone and dihydrochalcone structures, whereas chalcones underwent reduction to dihydrochalcones and cyclisation to a benzo-γ-pyrone moiety. Substrates with a C-2-C-3 double bond (flavones and isoflavones) were not transformed by Stenotrophomonas maltophilia KB2.