Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Institute of Eco-Chongming (IEC), 3663 North Zhongshan Road, Shanghai 200062, China.
Department of Microbiology, RIBES, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands.
J Hazard Mater. 2023 Mar 5;445:130558. doi: 10.1016/j.jhazmat.2022.130558. Epub 2022 Dec 5.
Benzimidazole fungicides are frequently detected in aquatic environments and pose a serious health risk. Here, we investigated the metabolic capacity of the recently discovered complete ammonia-oxidizing (comammox) Nitrospira inopinata and kreftii to transform a representative set of benzimidazole fungicides (i.e., benzimidazole, albendazole, carbendazim, fuberidazole, and thiabendazole). Ammonia-oxidizing bacteria and archaea, as well as the canonical nitrite-oxidizing Nitrospira exhibited no or minor biotransformation activity towards all the five benzimidazole fungicides. In contrast, the investigated comammox bacteria actively transformed all the five benzimidazole fungicides, except for thiabendazole. The identified transformation products indicated hydroxylation, S-oxidation, and glycosylation as the major biotransformation pathways of benzimidazole fungicides. We speculated that these reactions were catalyzed by comammox-specific ammonia monooxygenase, cytochrome P450 monooxygenases, and glycosylases, respectively. Interestingly, the exposure to albendazole enhanced the expression of the antibiotic resistance gene acrB of Nitrospira inopinata, suggesting that some benzimidazole fungicides could act as environmental stressors that trigger cellular defense mechanisms. Altogether, this study demonstrated the distinct substrate specificity of comammox bacteria towards benzimidazole fungicides and implies their significant roles in the biotransformation of these fungicides in nitrifying environments.
苯并咪唑类杀菌剂在水生环境中经常被检测到，对健康构成严重威胁。在这里，我们研究了最近发现的完全氨氧化（comammox）硝化螺旋菌在转化一组代表性的苯并咪唑类杀菌剂（即苯并咪唑、阿苯达唑、多菌灵、呋菌唑和噻菌灵）方面的代谢能力。氨氧化细菌和古菌以及经典的亚硝酸盐氧化菌硝化螺旋菌对所有五种苯并咪唑类杀菌剂均没有或很少有生物转化活性。相比之下，所研究的 comammox 细菌积极地转化了所有五种苯并咪唑类杀菌剂，除了噻菌灵。鉴定的转化产物表明，苯并咪唑类杀菌剂的主要生物转化途径为羟化、S-氧化和糖基化。我们推测这些反应分别由 comammox 特异性氨单加氧酶、细胞色素 P450 单加氧酶和糖苷酶催化。有趣的是，暴露于阿苯达唑增强了硝化螺旋菌在opinata 中抗生素抗性基因 acrB 的表达，表明一些苯并咪唑类杀菌剂可能作为环境胁迫物，触发细胞防御机制。总的来说，这项研究表明了 comammox 细菌对苯并咪唑类杀菌剂的独特的底物特异性，并暗示了它们在硝化环境中这些杀菌剂的生物转化中的重要作用。
