The effect of a static magnetic field on the acclimation of activated sludge with high polyhydroxyalkanoate (PHA) storage capacity was evaluated under aerobic dynamic feeding (ADF) conditions. The acclimation processes were carried out in Sequence Batch Reactors (SBRs) with static magnetic field intensities of 42, 21, 7, or 0 mT. Static magnetic exposure significantly influenced the PHA accumulation in activated sludge. PHA content in biomass reached 66% (on a COD basis) at a magnetic field intensity of 21 mT and an organic load of 5.42 g L-1, which was 16% higher than that of the control. Analysis by PCR-DGGE showed that the underlying mechanism might involve a change in the dominant species of microorganism in each reactor in response to the static magnetic field. (C) 2010 Elsevier Inc. All rights reserved.