Experimental study of the effects of heavy metal ions on the hydrogen production performance of Rhodobacter sphaeroides HY01

A newly isolated photosynthetic bacterium, Rhodobacter sphaeroides HY01 showed high hydrogen production performance and good flexibility on genetic modification. In order to investigate its potential on using wastewater containing heavy metal ions for photosynthetic hydrogen production, the effects of four conventional heavy metal ions, Pb²⁺, Cu²⁺, Cr⁶⁺ and Cd²⁺, on the photosynthetic hydrogen production performance of R. sphaeroides HY01 were studied. The results suggested that the concentration of Pb²⁺ 0.5 mg/L, Cu²⁺ 0.05 mg/L, Cr⁶⁺ 0.05 mg/L, Cd²⁺ 20 mg/L showed maximum positive effects on the hydrogen production rates and yields. This strain cultured in different heavy metal ions at optimum concentrations showed similar growth curves and optical density. The removal efficiency of heavy metal ions were determined to be 65%–76% for Cd²⁺, 54%–80% for Cr⁶⁺, 30%–38% for Pb²⁺and 96%–100% for Cu²⁺. The results suggest that HY01 was sensitive to Cr⁶⁺ and Pb²⁺, and relative of high tolerance to Cu²⁺ and Cd²⁺.