Active metal-cycling microbial communities of polymetallic nodules from the Eastern Pacific Ocean

The rising demand for minerals and metals is encouraging the great international interest for alternative sources in the deep sea. Deposits of deep-sea polymetallic nodules attracted the attention for a long time because they are rich in nickel, copper, cobalt, and rare earth elements. The environmental consequences of large-scale mining of polymetallic nodules are currently less known. In 2019 the Belgian and German licence area in the Clarion-Clipperton Zone (Eastern Pacific) were studied to obtain further baseline characteristics of the 4000 m deep polymetallic nodule fields. Here, we present: i) diversity and distribution of the present & active microbial communities of polymetallic nodules and ii) abundance and activity of relevant metal-cycling microorganisms by quantification of extracellular enzyme activity and 16S rRNA amplicon sequencing. Further we aim to enrich potential metal-cycling microorganisms and investigate microbial metabolisms by metagenomic/-transcriptomic from polymetallic nodules. Our results may provide a new set of tools for monitoring ecosystem impacts associated with deep-sea polymetallic nodule mining. New regulations are required to protect these areas from irreversible anthropogenic impacts