Novel insights into aerobic denitrifying bacterial communities augmented denitrification capacity and mechanisms in lake waters

Scanty attention has been paid to augmenting the denitrification performance of polluted lake water by adding mix-cultured aerobic denitrifying bacterial communities (Mix-CADBCs). In this study, to solve the serious problem of nitrogen pollution in lake water bodies, aerobic denitrifying bacteria were added to lake water to enhance the nitrogen and carbon removal ability. Three Mix-CADBCs were isolated from lake water and they could remove >94 % of total nitrogen and dissolved organic carbon, respectively. The balance of nitrogen analysis shown that >70 % of the initial nitrogen was converted to gaseous nitrogen, and <11 % of the initial nitrogen was converted into microbial biomass. The batch experiments indicated that three Mix-CADBCs could perform denitrification under various conditions. According to the results of nirS-type sequencing, the Hydrogenophaga sp., Prosthecomicrobium sp., and Pseudomonas sp. were dominated genera of three Mix-CADBCs. The analysis of network indicated Pseudomonas I.Bh25.14 and Vogsella LIG4 were correlated with the removal of total nitrogen (TN) and dissolved organic carbon in the Mix-CADBCs. Compared with lake raw water, the addition of three Mix-CADBCs could promote the denitrification capacity (the removal efficiencies of TN > 78.72 %), microbial growth (optical density increased by 0.015-0.138 and the total cell count increased by 2 times), and organic degradation ability (the removal efficiency chemical oxygen demand >38 %) of lake water. In general, the findings of this study demonstrated that Mix-CADBCs could provide a new perspective for biological treatment lake water body.