Polyphosphate accumulating organisms are responsible for enhanced biological phosphate removal from wastewater, where they grow embedded in a matrix of extracellular polymeric substances. Little is known about the composition and dynamics of those proteins and their production by the different microorganisms. Tomás-Martínez et al., (2022) studied the turnover of proteins and polysaccharides in extracellular polymeric fractions of an enrichment culture of polyphosphate accumulating organisms using an anaerobic-aerobic sequencing batch reactor simulating EBPR conditions. Finally, the carbon source was switched to 13C-labelled acetate to study the protein turnover. Samples were collected at the end of each aerobic phase.