Aerobic biotransformation of decalin (decahydronaphthalene) by Rhodococcus spp.

Mixed bacterial cultures aerobically transformed decalin (decahydronaphthalene) dissolved in an immiscible carrier phase (heptamethylnonane; HMN) in liquid medium. Conversion was enhanced in the presence of decane, a readily degraded n-alkane, and/or HMN. Four Rhodococcus spp. isolates purified from one of the mixed cultures were active against decalin in the presence of n-decane, but their ability to use decalin as a sole carbon source for growth could not be sustained. Isolate Iso 1a oxidized decalin under co-metabolic conditions with decane vapours as the primary carbon source. Mass spectrometry and comparison to authentic standards showed that the oxidized products of decalin biotransformation were 2-decahydronaphthol and 2-decalone. Some evidence of ring-opening was obtained, but the possible ring-opened product was not definitively identified. These results are consistent with co-metabolic oxidation of decalin by enzymes active toward n-alkanes.