Lycopene extraction and titration

The lycopene yields at different conditions were measured. Specifically, the bacteria cells cultured for 96 h at different conditions were harvested by centrifugation at 5000 × g for 5 min. The collected bacteria were washed twice with 1.0 g L^–1 NaCl. The cells were dried at 70 °C overnight to remove the water. Subsequently, lycopene in R. palustris bio-actuator was extracted with 3 mL mixed reagent of n-hexane and methanol (1:1 v/v). The mixed solution was vortexed for 5 min and then centrifugated at 7500 × g for 10 min at 4 °C. Finally, the exacted lycopene in supernatant was collected. The concentration of lycopene was measured by the Agilent 1260 Infinity II HPLC system (Agilent, Palo Alto, CA, USA). This involved a C18 column (4.6 × 100 mm, Agilent) with the mobile phase consisted of acetonitrile/methanol/chloroform (42.5:42.5:15 v/v/v). The flow rate was set at 1.0 mL min^–1 and the injection amount was set at 10 uL. The final concentrations of CCCP, rotenone, AQDS and HA used in this manuscript are 1 μM, 100 μM, 250 μM and 0.5 mg/mL respectively.