Increased Pollution-Induced Bacterial Community Tolerance to Sulfadiazine in Soil Hotspots Amended with Artificial Root Exudates
Increased Pollution-Induced Bacterial Community Tolerance to Sulfadiazine in Soil Hotspots Amended with Artificial Root Exudates
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DOI：
10.1021/es803546y
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发表时间：
2009-04-15
影响因子：
11.4
通讯作者：
Nybroe, Ole
中科院分区：
文献类型：
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作者：
Brandt, Kristian K.;Sjoholm, Ole R.;Nybroe, Ole
磺胺嘧啶（SDZ）残留是土壤中的一种重要污染物，可能会增加环境中的抗生素耐药性。我们的主要目的是比较污染诱导的社区容忍度（PICT）的发展，SDZ浓度水平在散装土壤和营养修正土壤热点。农业土壤微宇宙修正与不同浓度的SDZ与或不每周添加人工根系分泌物对应于现实的根沉积速率。通过[H-3]亮氨酸掺入技术测定，细菌群落对SDZ残留物的耐受性随着SDZ暴露量的增加而逐渐增加，并且在土壤热点中显著增加（LOEC为1 μ g/kg）。基于流式细胞术单细胞酯酶探测的替代PICT方法未能证明SDZ的影响。细菌的生长速率（[H-3]亮氨酸掺入）显着减少，在散装土壤和热点24小时后，修正与环境相关浓度的SDZ，而土壤呼吸保持不受影响，即使在100微克SDZ g（-1）。我们的研究第一次证明了一个急剧增加的PICT响应的土壤细菌群落由于增加碳基质修正本身。因此，热点土壤环境，如根际和粪肥-土壤界面可能包括对抗生素具有抗性或耐受性的细菌增殖的关键位点。
Sulfadiazine (SDZ) residues constitute an important pollutant in soils that may increase environmental reservoirs of antibiotic resistance. Our primary aim was to compare the development of pollution-induced community tolerance (PICT) to SDZ concentration levels in bulk soil and nutrient amended soil hotspots. Agricultural soil microcosms were amended with different concentrations of SDZ with or without weekly additions of artificial root exudates corresponding to realistic rhizodeposition rates. Bacterial community tolerance to SDZ residues, as determined by the [H-3]leucine incorporation technique, increased progressively with elevated SDZ exposure, and was significantly increased in soil hotspots (LOEC of 1 mu g kg(-1)). An alternative PICT approach based on single-cell esterase probing by flow cytometry failed to demonstrate SDZ impacts. Bacterial growth rates ([H-3]leucine incorporation) were significantly reduced in both bulk soil and hotspots 24 h after amendment with environmentally relevant concentrations of SDZ, while soil respiration remained unaffected even at 100 mu g SDZ g(-1). Our study for the first time demonstrates a drastically increased PICT response of a soil bacterial community due to increased carbon substrate amendment per se. Hence, hotspot soil environments such as rhizosphere and manure-soil interfaces may comprise key sites for proliferation of bacteria that are resistant or tolerant to antibiotics.