Fig. 7.

The sulfide oxidation activity of immobilized cells was increased after repeated use and culturing. The experiments were carried out in 50-mL centrifuge tube containing 10 mL of MM at 30 °C, 180 rpm. NaHS was added to 2 mM to initiate the reaction in each cycle and was completely oxidized within 40 min. After each reaction, the immobilized cells were washed with water and re-incubated in fresh MM with glucose. The cycle of sulfide oxidation was performed every 12 h. a G. oxydans 621H immobilized cells with Fe₃O₄ nanoparticles; b G. oxydans 621H immobilized cells. Averages (n ≥ 3) with standard deviations (error bar) were shown