Our results suggest that application of ozonated water may be useful in reducing the number of C. albicans on denture plates.

a-Ionone, a-methylionone, and a-isomethylionone were converted by Aspergillus niger JTS 191. The individual bioconversion products from a-ionone were isolated and identified by spectrometry and organic synthesis. The major products were cis-3-hydroxy-a-ionone, trans-3-hydroxy-a-ionone, and 3-oxo-a-ionone. 2,3-Dehydro-a-ionone, 3,4-dehydro-o-ionone, and 1-(6,6-dimethyl-2-methylene-3-cyclohexenyl)-buten-3-one were also identified. Analogous bioconversion products from a-methylionone and a-isomethylionone were also identified. From results of gas-liquid chromatographic analysis during the fermentation, we propose a metabolic pathway for a-ionones and elucidation of stereochemical features of the bioconversion. lonones and their derivatives are widely distributed in nature. They are important constituents of many kinds of essential oils and are presumably generated from carot-* Corresponding author.

Aspergillus niger JTS 191 was selected from many microorganisms tested as capable of converting ionones to other compounds having aromas. The individual transformation products from ,B-ionone were isolated and identifled by comparison with synthetically derived compounds. The major products were (R)-4hydroxy-f8-ionone and (S)-2-hydroxy-fl-ionone. 2-Oxo-, 4-oxo-, 3,4-dehydro-, 2,3dehydro-4-oxo-, 3,4-dehydro-2-oxo-, (S)-2-acetoxy-, (R)-4-acetoxy-, and 5,6epoxy-,8-ionone and 4-(2,3,6-trimethylphenyl)-but-3-en-2-one were also identified. Analogous transformation products of ,B-methylionone also were identified. Based on gas-liquid chromatographic analysis during the fermentation, we propose two main oxidative pathways of/3-ionone. The results of this study suggest that these transformations of,B-ionones may be useful as tobacco-flavoring compounds.

Muchattention has been paid to the aroma compounds formed by degradation of carotenoids in plants.:) In the previous paper, the usefulness of the microbial transformation for the preparation of these aromacompounds was demonstrated; jS-ionone was converted to more than 13 compounds containing (S)-2hydroxy-/?-ionone and (7?)-4-hydroxy-/?

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The effect of mouthrinses and topical application of chlorhexidine on the development of dental plaque and gingivitis in man;