Utilization of Nitrite as a Nitrogen Source by Microcystis aeruginosa

To investigate the effect of nitrite on growth of Microcystis aeruginosa and utilization of nitrite by cyanobacteria, the growth curve, the intracellular nitrite content and nitrite oxidoreductase(NOR)of M. aeruginosa under different nitrite concentration and the changes of concentrations of nitrite, nitrate and ammonium in the culture medium had been measured. Our results showed that both nitrite concentration and nitrate concentration decreased with cyanobacteria culturing in the medium containing 10 mg NO 2- -N·L-1, meanwhile, intracellular nitrite concentration increased with increase of nitrite concentration in culture medium, indicated that M. aeruginosa could uptake nitrite and nitrate simultaneously, moreover, the increase of nitrite concentration could promote nitrite uptake. However, in medium of 20, 30 mg NO 2--N·L-1, the nitrate concentration increased with nitrite concentration decreasing, and NOR was observed, revealing the nitrite might be oxidated to nitrate by NOR. Our results also showed that the growth of cyanobacteria was inhibited under high nitrite concentrations(over 10 mg NO2--N·L-1).