soil microbial community structure Grote Nete river basin

Metals and radionuclides can exert a persistent pressure on the soil microbial community, which is essential for a healthy soil ecosystem. However, little is known on the effect of long-term co-contamination of metals and radionuclides. We investigated the impact of historical discharges of the phosphate and nuclear industry on the microbial community in a river basin in Belgium. Eight locations were sampled along a transect to the river edge and one control location further in the field. A clear metal and radionuclide contamination gradient was shown. Through a combination of detailed chemical analysis, 16S rRNA gene sequencing, shotgun metagenomics and targeted toxicity experiments, a relation between the chemical parameters and the bacterial community structure was demonstrated. Although no difference in biomass was observed between locations, communities originating from contaminated locations were more adapted to metal stressors compared to control communities. Furthermore, nitrification, an important soil process, was affected in the contaminated locations. In conclusion, these results clearly indicate that long-term metal and radionuclide pollution impacts the microbial community structure and functionality. Moreover, this study provides important fundamental insights into microbial community dynamics in co-metal-radionuclide contaminated sites and could facilitate identifying sites for targeted isolations of adapted strains towards bioremediation applications.