Bioremediation of 27 Micropollutants by Symbiotic Microorganisms of Wetland Macrophytes

Background: Micropollutants in bodies of water represent many challenges. We addressedthese challenges by the application of constructed wetlands, which represent advanced treatmenttechnology for the removal of micropollutants from water. However, which mechanisms specificallycontribute to the removal efficiency often remains unclear. Methods: Here, we focus on the removalof 27 micropollutants by bioremediation. For this, macrophytesPhragmites australis,Iris pseudacorusandLythrum salicariawere taken from established wetlands, and a special experimental set-up wasdesigned. In order to better understand the impact of the rhizosphere microbiome, we determinedthe microbial composition using 16S rRNA gene sequencing and investigated the role of identifiedgenera in the micropollutant removal of micropollutants. Moreover, we studied the colonizationof macrophyte roots by arbuscular mycorrhizal fungi, which are known for their symbiotic rela-tionship with plants. This symbiosis could result in increased removal of present micropollutants.Results: We foundIris pseudacorusto be the most successful bioremediative system, as it removed22 compounds, including persistent ones, with more than 80% efficiency. The most abundant generathat contributed to the removal of micropollutants werePseudomonas, Flavobacterium, Variovorax,Methylotenera, Reyranella, AmaricoccusandHydrogenophaga.Iris pseudacorusexhibited the highest colo-nization rate (56%). Conclusions: Our experiments demonstrate the positive impact of rhizospheremicroorganisms on the removal of micropollutants.