Identification and monitoring of nitrification and denitrification genes in Klebsiella pneumoniae EGD-HP19-C for its ability to perform heterotrophic nitrification and aerobic denitrification

Microbes capable of performing heterotrophic nitrification and aerobic denitrification simultaneously have application in nitrogen level management in effluent treatment plants. Klebsiella pneumoniae EGD-HP19-C is a metabolically versatile bacterium capable of utilising NH3-N, NO2-N and NO3-N as sole sources of nitrogen. The annotation was done for the genes involved in N-assimilation and N-dissimilation pathways from the draft genome sequences of this bacterium (NCBI GenBank accession no. AUTW02000000.1). The sequence data also suggested possible existence of plasmid associated with this bacterium. Multiple gene sequence alignments of glutamine synthetase (gln), hydroxylamine reductase (har), nitrite reductase (nir), nitric oxide reductase (nor), assimilatory nitrate reductase (nas) and respiratory nitrate reductase (nar) genes from EGD-HP19-C genome were performed to compare sequence identities with that of closely related bacterial species. The metabolic pathways were mapped using KAAS and 3D structures for representative enzyme sub-units were also elucidated. The study suggested that the organism, though it has incomplete nitrification and denitrification pathways still removes the inorganic nitrogen content from the system via ammonification reaction.