To analyze (−)-α-bisabolol production, the culture broth was centrifuged at 13,000 rpm for 10 min to separate the overlaid n-dodecane phase. The recovered n-dodecane-phase was subsequently analyzed for (−)-α-bisabolol by GC and GC-mass spectrometry (GC–MS). The identification of (−)-α-bisabolol was conducted by GC–MS (5977A MSD) with a HP-5MS column (30 m × 0.250 mm × 0.25 µm, Agilent, Santa Clara, USA). The column flow was maintained at 1 mL/min. The oven temperature was initially held at 60 °C for 2 min, increased by 5 °C/min to 300 °C, and held at 300 °C for 10 min. (−)-α-Bisabolol (Cat. No. 23089-26-1, Sigma Aldrich) was used as the standard, and was confirmed through the GC-MS software, Mass Hunter (Agilent, Santa Clara, USA). The quantification of (−)-α-bisabolol was performed using GC equipped with a flame ionization detector (FID) with a HP-5 column (30 m × 0.320 mm × 0.25 µm) at a flow rate of 1 mL/min. The starting temperature of the oven was 60 °C for 2 min, increased at 5 °C/min to 200 °C, held at 200 °C for 2 min, increased by 50 °C/min to 300 °C, and held at 300 °C for 5 min. Helium was used as the carrier gas with an inlet pressure of 5.58 psi. The (−)-α-bisabolol concentration produced by engineered E. coli was determined as follows:\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(-) {\text{-}} \alpha {\text{-bisabolol }}\left[{\text{mg}}/{\rm L} \right] = \frac{{\left[ {\left( - \right) {\text{-}} \alpha {\text{-bisabolol in }}n-{\text{ dodecane phase}}} \right] \times \left[ {{\text{volume of }}n-{\text{ dodecane phase}}} \right]}}{{\left[ {\text{volume of medium phase}} \right]}}$$\end{document}(-)-α-bisabololmg/L=--α-bisabolol inn-dodecane phase×volume ofn-dodecane phasevolume of medium phase