The Arthrobacter sp. ZH(2) strain was found to efficiently degrade di-n-butyl phthalate, the optimal temperature and pH conversion conditions of which were 30 degrees C and 9.0, respectively. The degradation of DBP was best fitted by first-order kinetic equation and the half-life was 10.19 h. ZH(2) preferentially utilized DBP rather than dimethyl phthalate (DMP) when a minimal salt medium was added with a mixture of phthalate acid esters (PAEs) and the degradation of DMP and DBP could not induce the degradation of di-n-octyl phthalate (DOP). Partial sequences of the 3,4-phthalate dioxygenase gene were amplified from ZH(2). The expression ratio of 3,4-phthalate dioxygenase gene increased from 1-fold to 28.84-fold when the DBP concentration was increased from 0 to 500 mg per I. To our knowledge, this is the first report regarding the detection of the response of the 3,4-phthalate dioxygenase gene to different concentrations of DBP using reverse transcription quantitative PCR (RT-qPCR). (C) 2012 Published by Elsevier Ltd.