Atrazine, one of the most widely used pesticides, is a relatively hydrophobic organic pollutant (HOP) that contaminates ground and surface waters. Bioremediation of this pesticide by the bacterium Pseudomonas sp. strain ADP could successfully be performed in a pure aqueous system, with a specific growth rate of 0.0575 h(-1) utilizing 100 mg/L of atrazine as a sole nitrogen source. However, growth rate inhibition was observed at higher pesticide concentrations. Liquid-core capsules containing dibutyl sebacate were shown to efficiently extract atrazine from water by equilibrium partitioning. They could subsequently be used as a reservoir for the controlled delivery of the pesticide to the degrading bacteria. Maximum growth rates were found to be constant for the different pesticide concentrations, with values around 0.06h(-1). Compared to pure aqueous and classical two-phase systems [Daugulis AJ. Two-phase partitioning bioreactors: a new technology platform for destroying xenobiotics. Trends Biotechnol 2001; 19(11):457-62], the use of liquid-core capsules for performing two-phase biodegradation offers the advantages of reduction of both pollutant and organic phase toxicity thereby allowing high concentrations of pesticides to be degraded. (c) 2006 Elsevier Inc. All rights reserved.