Oleic acid concentration in fadL-fadD transformant and control E. coli cells at various concentrations of IPTG. Intracellular concentration of oleic acid in control E. coli BL21(DE3) host cells (YELLOW) and fadL-fadD transformant (GRAY). E. coli cells were incubated in LB + oleic acid (10 µM) medium and induced with 0 µM, 40 µM or 400 µM IPTG for 6 hrs.