IPP and DMAPP, precursors of FPP, are essential metabolites in E. coli that are used for tRNA prenylation, synthesis of quinone and dolichol for respiration, and cell wall biosynthesis . Thus, the metabolic balance of IPP and DMAPP between endogenous essential metabolism and exogenous (−)-α-bisabolol production plays a crucial role in improving production of (−)-α-bisabolol and alleviation of growth inhibition. To determine the optimal IPP and DMAPP pool balancing conditions in the engineered E. coli harboring the entire MVA pathway and MrBBS genes (pSNA-MrBBS), we examined if cultivation media and glycerol availability limit (−)-α-bisabolol production. To do this we tested different media and concentrations of glycerol ranging from 0 to 3.5% (w/v) (Fig. 5a). E. coli DH5α containing the pSNA-MrBBS produced the highest concentration of (−)-α-bisabolol (24.2 mg/L) in TB medium without the addition of an additional carbon source (Fig. 5a). (−)-α-Bisabolol production was dependent on the amount of provided glycerol in the TB medium. With 1% (w/v) glycerol, (−)-α-bisabolol concentration was 38.3 mg/L, approximately 1.4-fold higher than the concentration of (−)-α-bisabolol obtained without the inclusion of glycerol. However, 3.5% (w/v) of glycerol concentration did not show further improvement of (−)-α-bisabolol production (Fig. 5a). Because cell growth of E. coli DH5α varied in different culture media, the differences in (−)-α-bisabolol production are partly due to differences in growth (Figure S3A).