Influence of illumination, oxygen, pH and salinity on growth and nitrite removal effect of Rhodopseudomonas palustris strain 2-8

We used Rhodopseudomonas palustris strain 2-8, a denitrifying non-sulfur photosynthetic bacterium, to study its growth and nitrite removal effect with different illumination-oxygen combinations, pH level and NaCl concentrations. The results show that illumination without oxygen is best for the strains growth and nitrite removal, with a nitrite removal efficiency of (91.331.27)% after 25 h inoculation; pH 7.0 is best for its growth and nitrite removal, and the nitrite removal efficiency reaches (95.584.34)% after 25 h inoculation, however, it does not grow at pH below 5.0 or above 9.0. Moreover, the strain grows best and removes nitrite most quickly with NaCl culture medium of 0.0% or 0.4%, but with a 0.8%~2.0% NaCl concentration, its growth and nitrite removal effect weaken with the increasing concentration. These four environmental factors influence the nitrite removal effect of stain 2-8 by influencing its growth.