Coupling of metabolism and bioconversion: microbial esterification of citronellol with acetyl coenzyme A produced via metabolism of glucose in an interface bioreactor

Microbial esterification of citronellol with acetyl coenzyme A (acetyl-CoA) produced via metabolism of glucose was performed with Hansenula saturnus IFO 0809 in an interface bioreactor by using a hydrophilic carrier (an agar plate or an agar-coated filter pad) and a hydrophobic organic solvent (decane). An increase in the glucose concentration on an agar plate led to a decrease in oxidation of citronellol and an increase in the amount of citronellyl acetate. Fed-batch addition of citronellol efficiently alleviated substrate toxicity and resulted in the accumulation of high levels of citronellyl acetate. Furthermore, triple coupling of acetyl-CoA formation, microbial reduction of citronellal to citronellol, and esterification of the resulting citronellol with acetyl-CoA was also an efficient way to prepare citronellyl acetate. By using coupling systems, citronellyl acetate could be efficiently produced without any acetyl donor