The effect of mevalonate concentration on (−)-α-bisabolol production (a) and final OD600 (b) from engineered E. coli harboring pTSN-MrBBS and pSSN12Didi. Cells were grown at 30 °C in LB medium supplemented with different concentrations of mevalonate and 20% (v/v) n-dodecane for 48 h. Data represent averages from three replicate cultures; error bars show SD