Production of tobacco aroma from lutein. Specific role of the microorganisms involved in the process

A mixed culture formed by Bacillus sp. and Geotrichum sp. produced tobacco aroma compounds from the carotenoid lutein through the formation of the intermediate -ionone. Both microorganisms can grow independently in a medium supplemented with lutein, but only Geotrichum produces -ionone. This intermediate was incorporated by the bacilli, converted to aroma and this product excreted to the culture medium. Bacillus sp. did not utilize -ionone for growth but modified it. We conclude that, in the bioconversion of lutein to products with tobacco aroma, Geotrichum sp. is involved in carotenoid oxidation to produce -ionone and Bacillus sp. is responsible for the norisoprenoid reduction to produce 7,8-dihydro--ionone and 7,8-dihydro--ionol.