The impact of ferrous iron on DNRA activity and microbial communities in sedimentary environments

Dissimilatory Nitrate Reduction to Ammonium (DNRA) is a critical nitrogen transformation process in sedimentary environments that plays an essential role in retaining 'fixed' nitrogen within ecosystems and preventing loss through denitrification processes. Ferrous iron (Fe2+) has been shown to enhance DNRA over denitrification, consistent with proposed Fe2+-DNRA mechanisms. Despite growing attention to the role of Fe2+ in DNRA activity and its impact on microbial communities, it still needs to be fully understood. This PhD thesis aims to investigate how Fe²⁺ affects DNRA activity and the microbial communities in diverse aquatic sediments using laboratory experiments and advanced genomic analysis combined with culture-based techniques.