Sieving and characterization of a heterotrophic nitrifying-aerobic denitrifying-phosphorus-accumulating bacterial strain,Klebsiella pneumoniae A15
A strain of Klebsiella pneumoniae A15 with heterotrophic nitrification-aerobic denitrification and phosphorus accumulation was isolated from activated sludge of a wastewater treatment plant using an anoxic/aerobic sequencing batch system with starch as the sole carbon source.Its optimal growth conditions:carbon source was sodium citrate,C/N was 30,P/N was 0.2,and pH was 7.Under the optimal conditions,the maximum removal rates of ammonia nitrogen,nitrite,and nitrate were 96.27％,99.22％,and 100％,respectively;and the corresponding rates of removal were 1.77,2.08 and 1.86mg/(L·h).The strain was effective in removing phosphorus at concentrations of 8mg/L and 1300mg/L COD with maximum removal rates of 100％and 95％,respectively.Nitrogen balance analysis revealed that the bacterium could utilize ammonia,nitrate and nitrite nitrogen to produce gaseous nitrogen,and showed excellent heterotrophic nitrification and aerobic denitrification activities.Analysis of intracellular phosphorus and phosphorus in the EPS of the strain combined with DAPI staining revealed that 82％of the phosphorus was stored in the cells of the strain and in the form of polyphosphates,with the remaining phosphorus in the EPS.Successful amplification of napA,nirS,nosZ and ppk genes of the strain also indicated its aerobic denitrification and phosphorus accumulation capacity.The present study demonstrates a bacterial strain with specific functions in the denitrification and phosphorus removal system.
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