Ability of Novosphingobium aromaticivorans of growing with aromatic compounds adsorbed to granular activated carbon might be relevant for the stable occurrence of Sphingomonadaceae in adsorption modules in fourth clarification stages of wastewater treatment plants

Activated carbon filters are increasingly being installed in sewage treatment plants to remove organic micropollutants from purified wastewater through a physicochemical adsorption process. Microbial biodegradation also contributes to the removal of micropollutants in these filters but the microbiomes and the underlying processes are mainly unexplored. Particularly, it is unknown whether active microbial desorption of micropollutants takes place. We studied the ability of strain N. aromaticivorans DSM 12444, which is known to degrade synthetic chemicals. Laboratory experiments with strains DSM12444 and the Pseudomonads showed that strain DSM12444 reached a significantly higher final optical density with benzoate and salicylate that was pre-adsorbed to granular activated carbon than strain Teo15 and p. salic, respectively. Transcriptomic analysis of strain DSM1244 during growth with benzoic acid showed differential gene expression in the presence and absence of GAC. In particular, a different pathway for degrading aromatic compounds and two genes for hemerythrin-domain containing proteins, which can serve as redox sensors, were unregulated in the presence of GAC.