BACKGROUND: The isomers of chlorotoluene (2-chlorotoluene, 3-chlorotoluene and 4-chlorotoluene) are considered to be toxic and to have a negative impact on humans and the environment. Therefore, issues related to their removal from the natural environment have become of increasing interest. RESULTS: The morphology of cells and colonies after long-term metabolic stress was significantly modified. Metabolic stress is suggested to be a determinant of bacteria cell surface properties. The chlorine atom position in chlorotoluenes has a strong impact on cell surface modification. When the chlorine atom was at the ortho or para position, a large increase in hydrophobicity (from40% to73% and from29% to 49%, respectively) and a decrease in the innermembrane permeability (from 0.31 to 0.24 mu mol L-1 min(-1) and from0.52 to 0.13 mu mol L-1 min(-1)) were observed. Moreover, Achromobacter sp. KW1 strain was found to exhibit good ability to degrade chlorotoluenes. The greatest difference in biodegradation between the stressed and non-stressed strains was observed for the cultures grown on 4-chlorotoluene and 3-chlorotoluene. CONCLUSIONS: Both long-term contact with hydrocarbons and the addition of surfactants demonstrated a beneficial effect on the biodegradation process. However, as a result of long-term contact with hydrocarbons, the bacteria studied were able to degrade chlorotoluenes faster and more effectively. (C) 2017 Society of Chemical Industry