Tracing carbon and nitrogen microbial assimilation in suspended particles in freshwaters

Abstract The dynamic interactions between dissolved organic matter (DOM) and particulate (POM) are central in nutrient cycling freshwater ecosystems. However, the molecular-level mechanisms of such still poorly defined. Here, we study spatial differences chemical (i.e., individual proteinaceous amino acids) microbial 16S rRNA) composition suspended sediments River Chew, UK. We then applied a compound-specific stable isotope probing (SIP) approach to test potential assimilation 13 C, 15 N-glutamate (Glu) N-NO 3 − into biomass by particle-associated communities over 72-h period. Our results demonstrate that particles is strongly influenced effluent sewage treatment works. Fluxes percentages both isotopically labelled substrates acids showed contrasting dynamics processing at each site linked primary biosynthetic metabolic pathways. Preferential molecule glutamate evidence its direct newly synthesised was obtained. provides quantitative molecular information on which low weight DOM mineralised water column compared an inorganic substrate. This paramount for better understanding fate aquatic