UNLABELLED: Bacteria form multicellular aggregates called biofilms. A crucial component of these aggregates is a protective matrix that holds the community together. Biofilm matrix composition varies depending upon bacterial species but typically includes exopolysaccharides (EPS), proteins, and extracellular DNA. IMPORTANCE: Here, we show that, to accommodate growing cellular biomass, newly produced Psl is deposited over existing Psl at the periphery of biofilm aggregates. We demonstrated that