Plasmids were transformed into E. coli BL21 (DE3) for expression. Overnight cultures were prepared by inoculating 10 mL of LB (supplemented with 50 μg mL -1 kanamycin) with a single colony and growing for 16 hours at 37 °C at 200 rpm. The overnight culture was then used to inoculate a baffled flask containing 400 mL autoinduction TB media and 50 μg mL -1 kanamycin and incubated at 37 °C at 200 rpm until optical density at 600 nm (OD600) of 0.4. The culture was cooled to 20 °C and delta-aminolevulinic acid was added to a final concentration of 0.5 mM and further incubated overnight at 20 °C at 200 rpm. Cells were centrifuged at 4000 rpm for 30 min and stored as pellets at -20 °C.