Influence of several metal ions on growth and nitrite removal of Rhodopseudomonas palustris strain 2-8

We supplemented different concentrations of Cu²⁺, Mg²⁺, Zn²⁺, Fe³⁺, Mn²⁺ to the substrate to study their influence on the growth and nitrite removal of Rhodopseudomonas palustris strain 2-8. It is found that 1×10^-7 mol · L^-1 Cu²⁺ improves but 1×10^-4 mol · L^-1 Cu²⁺ inhibits the growth and nitrite removal of strain 2-8;1×10^-6 mol · L^-1 and 1×10^-5 mol · L^-1 Cu²⁺ inhibit the growth but improve the nitrite removal. 1×10^-4 mol · L^-1 Mg²⁺ improves the growth and nitrite removal. Zn²⁺ has no significant influence on the growth but low concentration (1×10^-6mol · L^-1 and 1×10^-7mol · L^-1) of Zn²⁺ improves the nitrite removal, while high concentration (>1×10^-6 mol · L^-1) is the opposite. The higher the concentration of Fe³⁺ is, the better the growth is but the worse the nitrite removal is. Mn²⁺ inhibits the growth and 1×10^-6~1×10^-3 mol · L^-1 Mn²⁺ inhibits the nitirte removal. Except 1×10^-4 mol · L^-1 Cu²⁺ which inhibits nitrite removal greatly, the inhibition of the other metal ions becomes weaker with time.