Microbial transformation of menthol and menthane-3,4-diol

A bacterium isolated from sewage by enrichment on (−)-menthol will use as sole source of carbon (−)-menthol and the related compounds, (−)-isopulegol, (+)-isomenthol, (±)-neomenthol, geraniol, and menthane-3,4-diol, but not (+)-menthol and (+)-isopulegol. Medium from (−)-menthol grown cells contains menthone, 3,7-dimethyl-6-hydroxyoctanoic acid, and 3,7-dimethyl-6-oxo-octanoic acid. Cell suspensions incubated with (−)-menthol yielded the same intermediates. Metabolism of menthane-3,4-diol by this bacterium yielded the same oxo acid plus 4-hydroxy-3-keto-p-menthane. A pathway is proposed for the oxidation of menthol and menthane-3,4-diol by this organism.