Culturable nitrogen-transforming bacteria from sequential sedimentation biofiltration systems and their potential for nutrient removal in urban polluted rivers
Arnoldo Font-Nájera, Liliana Serwecińska, Joanna Mankiewicz‐Boczek
Abstract
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–NH 4 and 70.2% of N–NO 3 , while Str21, identified as Pseudomonas mandelii , removed up to 98.9% of N–NH 4 and 87.7% of N–NO 3 . The key functional genes nap A/ nar G and hao were detected for Bzr02, confirming its ability to reduce nitrate to nitrite and remove hydroxylamine. Str21 was detected with the genes nar G, nir S, nor B and nos Z, 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.