Characterisation of an efficient atrazine-degrading bacterium, Arthrobacter sp. ZXY-2: an attempt to lay the foundation for potential bioaugmentation applications

Abstract

In this study, strain <i>Arthrobacter</i> sp. ZXY-2, which displayed a strong capacity to degrade atrazine, was isolated and shown to be a potential candidate for bioaugmentation. The factors associated with the biodegrading capacity of strain ZXY-2 were investigated, and how these factors likely govern the metabolic characteristics that control bioaugmentation functionality was determined. The growth pattern of <i>Arthrobacter</i> sp. ZXY-2 followed the Haldane-Andrews model with an inhibition constant (<i>K</i>_i) of 52.76 mg L^-1, indicating the possible augmentation of wastewater treatment with relatively high atrazine concentrations (> 50 ppm). Real-time quantitative PCR (RT-qPCR) results showed a positive correlation between the atrazine degradation rate and the expression levels of three functional genes (<i>trzN</i>, <i>atzB</i>, and <i>atzC</i>), which helped elucidate the role of strain ZXY-2 in bioaugmentation. In addition, multiple copies of the <i>atzB</i> gene were putatively identified, explaining the higher expression levels of this gene than those of the other functional genes. Multiple copies of the <i>atzB</i> gene may represent a compensatory mechanism that ensures the biodegradation of atrazine, a feature that should be exploited in future bioaugmentation applications.