Bacterial communities associated with sediment particles were examined using PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing. Particle size influenced community structure, with attached bacterial assemblages separating into 63-125, 125-1000, and 1000-2000 microm fractions. Differences were particularly pronounced for the Verrucomicrobia-Planctomycetes which were significantly reduced on coarser particles. 10.1128/AEM.00923-08