In order to better understand how surfactants affect biodegradation of hydrophobic organic compounds (HOCs), Tween 80 and sodium dodecyl benzene sulfonate (SDBS), were selected to investigate effects on cell surface hydrophobicity (CSH), electron transport system (ETS) activities and phenanthrene biodegradation by Citrobacter sp. SA01. Tween 80 and SDBS increased CSH by 19.8-25.2%, ETS activities by 352.1-376.0 mu mol/g min, catechol 1,2-dioxygenase (C12) activities by 50.8-52.7 U/L, and phenanthrene biodegradation by 8.9-17.2% separately in the presence of 50 mg/L of surfactants as compared to in their absence. Lipopolysaccharide (LPS) release was 334.7 mu g/mg in the presence of both surfactants whereas in their absence only 8.6-44.4 mu g/mg of LPS was released. Thus, enhanced LPS release probably increased ETS and 02 activities as well as phenanthrene biodegradation by increasing CSH. The results demonstrate that surfactant-enhanced CSH provides a simple, yet effective strategy for field applications of surfactant-enhanced bioremediation of HOCs. (C) 2012 Elsevier Ltd. All rights reserved.