Rapid biodegradation of atrazine by Ensifer sp strain and its degradation genes

A bacterial strain (CX-T) capable of utilizing atrazine as a nitrogen source for growth was isolated from an industrial soil sample via enrichment culture. The isolate was identified as an Ensifer sp. which can metabolize atrazine (100 mg L-1) completely within 30 h in a liquid culture medium. Factors such as temperature, pH and the shaker speed were analyzed with regard to their effect on atrazine degradation in liquid medium. It was found that atrazine removal efficiency varied significantly depending on temperature (mean degradation efficiency: 54.30% at 25 degrees C, 99.71% at 30 degrees C and 84.7% at 35 degrees C, P<0.01) and is optimal under neutral to acidic conditions (pH 5, 91.54%; pH 7, 99.71%; pH 9, 91.71%, P<0.01), as well as low shaker speeds (100 rpm (99.38%) and 180 rpm (99.71%) P<0.01). Additionally through Polymerase Chain Reaction (PCR), degradation genes atzA, atzB, atzC, atzD, atzE and atzF were amplified successfully using highly conserved primers, while trzN and trzD were not detected. We propose these unique genes enabled the CX-T strain to mineralize atrazine, supported by the observation of its growth in the cyanuric acid medium. We conclude CX-T could be a useful bioremediation tool for atrazine polluted soils. (C) 2016 Elsevier Ltd. All rights reserved.