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 strain′s growth and nitrite removal,with a nitrite removal efficiency of (91.33±1.27)% after 25 h inoculation;pH 7.0 is best for its growth and nitrite removal,and the nitrite removal efficiency reaches (95.58±4.34)% 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.