Culturable nitrogen-transforming bacteria from sequential sedimentation biofiltration systems and their potential for nutrient removal in urban polluted rivers

Abstract

Novel heterotrophic bacterial strains—Bzr02 and Str21, effective in nitrogen transformation, were isolated from sequential sedimentation-biofiltration systems (SSBSs). Bzr02, identified as Citrobacter freundii, removed up to 99.0% of N–NH4 and 70.2% of N–NO3, while Str21, identified as Pseudomonas mandelii, removed up to 98.9% of N–NH4 and 87.7% of N–NO3. The key functional genes napA/narG and hao were detected for Bzr02, confirming its ability to reduce nitrate to nitrite and remove hydroxylamine. Str21 was detected with the genes narG, nirS, norB and nosZ, confirming its potential for complete denitrification process. Nitrogen total balance experiments determined that Bzr02 and Str21 incorporated nitrogen into cell biomass (up to 94.7% and 74.7%, respectively), suggesting that nitrogen assimilation was also an important process occurring simultaneously with denitrification. Based on these results, both strains are suitable candidates for improving nutrient removal efficiencies in nature-based solutions such as SSBSs.

Phylogenomic analysis of Citrobacter sp. strain AAK_AS5 and its metabolic capabilities to support nitrogen removal behavior

“…in nitrate removal through denitrification [122]. More recently, a novel heterotrophic C. freundii strain Bzr02 isolated from sequential sedimentation‐biofiltration systems (SSBSs) was shown to remove up to 99.0% of ammonia‐N and 70.2% of nitrate‐N that was further validated by the detection of genes nap A/ nar G and hao encoding enzymes for reduction of nitrate to nitrite and removal of hydroxylamine, respectively [123]. Microorganisms capable of performing both nitrification and denitrification by SND process in a single vessel under similar conditions have gained significance in wastewater treatment [96].…”