Performance and mechanism of nitrate removal by the aerobic denitrifying bacterium JI-2 with a strong autoaggregation capacity

Here, a new strain JI-2 of the strongly autoaggregating aerobic denitrifying bacteria was screened. The nitrate removal ability and autoaggregation mechanism of JI-2 were analyzed using the nitrogen balance and genomics technology. The nitrate removal rate was 27.05 mg N/(L.h) at pH 9.0 and C/N 8.0. The strain JI-2 removes nitrate via the aerobic denitrification and dissimilation pathways and removes ammonium via the assimilation pathway. 66.81 % nitrate was converted to cellular components under aerobic conditions. Complex nitrogen metabolism genes were detected in strain JI-2. C-di-GMP mediates the motility behavior of JI-2 by binding the FleQ and PilZ proteins, and regulating the expression of PslA. Furthermore, the mechanism of autoaggregation was verified by extracellular polymeric substance analysis. Meanwhile, the nitrate removal rates of strain JI-2 was 11.13-12.50 mg N/(L.h) in wastewater. Thus, strain JI-2 has good prospects for application in the treatment of nitrate wastewater.

Automated summary

A new strain JI-2 of strongly autoaggregating aerobic denitrifying bacteria was screened, and its nitrate removal ability and autoaggregation mechanism were analyzed. The study found that JI-2 had a high nitrate removal rate under alkaline and low carbon-to-nitrogen ratio conditions. It removes nitrate through aerobic denitrification and dissimilation pathways, and removes ammonium through an assimilation pathway. JI-2 strain has complex nitrogen metabolism genes, and C-di-GMP plays an important role in mediating its motility behavior and autoaggregation.