Abstract
BackgroundThe isolation of atrazine-degrading microorganisms with specific characteristics is fundamental for bioaugmenting the treatment of wastewater containing atrazine. However, studies describing the specific features of such microorganisms are limited, and further investigation is needed to improve our understanding of bioaugmentation.Results and conclusionsIn this study, strain Arthrobacter 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 Arthrobacter sp. ZXY-2 followed the Haldane–Andrews model with an inhibition constant (Ki) 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 (trzN, atzB, and atzC), which helped elucidate the role of strain ZXY-2 in bioaugmentation. In addition, multiple copies of the atzB gene were putatively identified, explaining the higher expression levels of this gene than those of the other functional genes. Multiple copies of the atzB gene may represent a compensatory mechanism that ensures the biodegradation of atrazine, a feature that should be exploited in future bioaugmentation applications.
Highlights
The isolation of atrazine-degrading microorganisms with specific characteristics is fundamental for bioaugmenting the treatment of wastewater containing atrazine
Evaluation of atrazine biodegradation Atrazine degradation by Arthrobacter sp. strain ZXY-2 was studied in a liquid enrichment medium
The atrazine degradation rate of strain ZXY-2 was examined under the following different culture conditions: an initial atrazine concentration range of 50–100 mg L−1, a pH range of 7.0–9.0, a carbon source range of 2–3 g L−1, and a temperature range of 30–35 °C
Summary
The isolation of atrazine-degrading microorganisms with specific characteristics is fundamental for bioaugmenting the treatment of wastewater containing atrazine. Primarily belonging to the genera Pseudomonas, Acinetobacter, Rhodococcus, Arthrobacter, Bacillus, Variovorax, and Citricoccus, have been isolated and utilised to degrade atrazine [11,12,13,14,15,16,17,18]. These strains have several common characteristics, such as high atrazine-degrading efficiency within broad pH or temperature ranges [15, 16, 19]. Without fundamental knowledge and a better understanding of the bioaugmentation process, it is difficult to broadly and deeply design and implement atrazine bioaugmentation in practice
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