Atrazine is a triazine herbicide that is widely used to control broadleaf weeds. Its widespread use over the last 50 years has led to the potential contamination of soils, groundwater, rivers, and lakes. Its main route of complete degradation is via biological means, which is carried out by soil microbiota using a 6-step pathway. The aim of the present study was to investigate whether application of atrazine to soil changes the soil bacterial community. We used 16S rRNA gene sequencing and qPCR to elucidate the microbial community structure and assess the abundance of the atrazine degradation genes atzA, atzD, and trzN in a Brazilian soil. The results obtained showed that the relative abundance of atzA and trzN, encoding triazine-initiating metabolism in Gram-negative and -positive bacteria, respectively, increased in soil during the first weeks following the application of atrazine. In contrast, the abundance of atzD, encoding cyanuric acid amidohydrolase—the fourth step in the pathway—was not related to the atrazine treatment. Moreover, the overall soil bacterial community showed no significant changes after the application of atrazine. Despite this, we observed increases in the relative abundance of bacterial families in the 4th and 8th weeks following the atrazine treatment, which may have been related to higher copy numbers of atzA and trzN, in part due to the release of nitrogen from the herbicide. The present results revealed that while the application of atrazine may temporarily increase the quantities of the atzA and trzN genes in a Brazilian Red Latosol soil, it does not lead to significant and long-term changes in the bacterial community structure.

中文翻译：

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阿特拉津暴露对巴西热带赤土土壤微生物群落结构的影响

阿特拉津是一种三嗪类除草剂，广泛用于控制阔叶杂草。过去 50 年的广泛使用导致了土壤、地下水、河流和湖泊的潜在污染。其完全降解的主要途径是通过生物手段，由土壤微生物群通过六步途径进行。本研究的目的是调查向土壤施用莠去津是否会改变土壤细菌群落。我们使用 16S rRNA 基因测序和 qPCR 来阐明巴西土壤中的微生物群落结构并评估莠去津降解基因 atzA、atzD 和 trzN 的丰度。获得的结果表明，在施用莠去津后的最初几周内，土壤中分别编码革兰氏阴性菌和阳性菌中三嗪启动代谢的atzA和trzN的相对丰度增加。相比之下，编码氰尿酸酰胺水解酶（该途径的第四步）的 atzD 的丰度与莠去津处理无关。此外，施用莠去津后，整体土壤细菌群落没有表现出显着变化。尽管如此，我们观察到阿特拉津处理后第 4 周和第 8 周细菌家族的相对丰度有所增加，这可能与 atzA 和 trzN 拷贝数较高有关，部分原因是除草剂释放了氮。目前的结果表明，虽然阿特拉津的施用可能会暂时增加巴西红土土壤中 atzA 和 trzN 基因的数量，但它不会导致细菌群落结构的显着和长期变化。