Biotransformation of citronellol by the basidiomycete Cystoderma carcharias in an aerated-membrane bioreactor

The basidiomycete Cystoderma carcharias transformed citronellol into 3,7-di methyl-1,6,7-octanetriol as the main product. 3,7-Dimethyl-6,7-epoxy-1-octa nol was identified as important intermediary product of the biotransformati on, and the allylic diols 2,6-dimethyl-2-octene-1,8-diol, 3,7-dimethyl-5-oc tene-1,7-diol and 3,7-dimethyl-7-octene-1,6-diol were found to be minor pro ducts, Microbial formation of rose oxide, a flavour-impact component, was o bserved for the first time. The formation of the main products was inhibite d by 70% after addition of 0.1 mmol 1(-1) cytochrome monooxygenase inhibito rs. Formation of 3,7-dimethyl-1,6,7-octanetriol was effective in a bioreact or with aeration over a coil of a hydrophobic microporous polypropene capil lary membrane. Production rates of up to 150 mg 1(-1) day(-1) were reached and led to a product concentration of 866 mg 1(-1) (conversion rate: 52%). The total loss of the added volatile substrate via the exhaust air was 4.5% when this aeration method was used.