Liu Zhiyuan, Han Lingxi, Zhang Xin, Chen Shiyu, Wang Xiuguo, Fang Hua
Tobacco Research Institute of Chinese Academy of Agricultural Sciences (CAAS), Qingdao 266101, PR China; Institute of Pesticide and Environmental Toxicology, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou 310058, PR China.
College of Horticulture, Qingdao Agricultural University, Qingdao 266109, PR China.
Environ Int. 2023 Nov;181:108303. doi: 10.1016/j.envint.2023.108303. Epub 2023 Nov 2.
Atrazine residues can pose serious threats to soil ecology and human health. Currently, the underlying relationship between soil microbial communities and the degradation genes associated with atrazine degradation remains unclear. In this study, the degradation characteristics of atrazine was investigated in ten different soil types. Further, diversity and abundance of degradation genes and succession of the bacterial community were also studied. The degradation of 10 mg/kg atrazine in different soil types exhibited an initial rapid trend followed by a gradual slowdown, adhering to the first-order kinetic equation. Atrazine significantly increased the absolute abundance of atz degradation genes. The increase in the absolute abundance of atzC gene was the largest, whereas that of atzA gene was the smallest, and the trzD gene was only detected in the Binzhou loam soil. Co-occurrence network analysis showed that the number of potential bacterial hosts of atzC was the highest compared with the other atz genes. Atrazine also altered the structural composition of the soil microbial community. The relative abundances of Ochrobactrum, Nocardiopsis, Lactobacillus, and Brevibacterium was increased in the atrazine-treated soils, while those of Conexibate, Solirubacter, and Micromonospora was decreased significantly compared with the control. Additionally, four atrazine-degrading bacterial strains Rhizobium AT1, Stenotrophomonas AT2, Brevibacterium AT3, and Bacillus AT4 were isolated from the atrazine-treated soils. After 14 d for inoculation, their degradation rate for 10 mg/L atrazine ranged from 17.56 % to 30.55 %. Moreover, the relative abundances of the bacterial genera, including these four isolates, in the atrazine-treated soil were significantly higher than those in the control, indicating that they were involved in the synergistic degradation of atrazine in the soil. This study revealed the degradation characteristics of atrazine, distribution of degradation genes, and succession of microbial communities, and explored the internal relationship between microbial community structure and atrazine degradation mechanisms in different soil types.
莠去津残留会对土壤生态和人类健康构成严重威胁。目前，土壤微生物群落与莠去津降解相关基因之间的潜在关系仍不明确。本研究调查了十种不同土壤类型中莠去津的降解特性。此外，还研究了降解基因的多样性和丰度以及细菌群落的演替。不同土壤类型中10 mg/kg莠去津的降解呈现出初期快速下降随后逐渐减缓的趋势，符合一级动力学方程。莠去津显著增加了atz降解基因的绝对丰度。atzC基因绝对丰度的增加最大，而atzA基因的增加最小，trzD基因仅在滨州壤土中被检测到。共现网络分析表明，与其他atz基因相比，atzC潜在细菌宿主的数量最高。莠去津还改变了土壤微生物群落的结构组成。与对照相比，在莠去津处理的土壤中，苍白杆菌属、诺卡氏菌属、乳杆菌属和短杆菌属的相对丰度增加，而锥状杆菌属、太阳杆菌属和小单孢菌属的相对丰度显著降低。此外，从莠去津处理的土壤中分离出四株莠去津降解细菌菌株，分别为根瘤菌AT1、嗜麦芽窄食单胞菌AT2、短杆菌AT3和芽孢杆菌AT4。接种14天后，它们对10 mg/L莠去津的降解率在17.56%至30.55%之间。此外，在莠去津处理的土壤中，包括这四株分离菌在内的细菌属的相对丰度显著高于对照，表明它们参与了土壤中莠去津的协同降解。本研究揭示了莠去津的降解特性、降解基因的分布以及微生物群落的演替，并探讨了不同土壤类型中微生物群落结构与莠去津降解机制之间的内在关系。
