Data_Sheet_1_Vancomycin and/or Multidrug-Resistant Citrobacter Freundii Altered the Metabolic Pattern of Soil Microbial Community.PDF

Despite many studies, our knowledge on the impact of antibiotics and antibiotic-resistant bacteria on the metabolic activity of soil microbial communities is still limited. To ascertain this impact, the community level physiological profiles (CLPPs) and the activity of selected enzymes (dehydrogenase, urease, and phosphatases) in soils treated with vancomycin (VA) and/or multidrug resistant Citrobacter freundii were determined during a 90-day experiment. A multivariate analysis and the resistance (RS)/resilience (RL) concept were used to assess the potential of native microorganisms to maintain their catabolic activity under exposure of VA and/or a high level of C. freundii. In addition, the dissipation rate of VA was evaluated in non-sterile (nsS) and sterile (sS) soils. The results revealed a negative impact of VA on the metabolic activity of soil microorganisms on days 1, 15, and 30 as was showed by a decrease in the values of the CLPP indices (10–69%) and the enzyme activities (6–32%) for treated soils as compared to the control. These observations suggested a low initial resistance of soil microorganisms to VA and/or C. freundii but they were resilient in the long term. Considering the mean values of the RS index, the resistance of measured parameters was categorized in the following order: alkaline phosphatase (0.919) > acid phosphatase (0.899) > dehydrogenase (0.853) > the evenness index (0.840) > urease (0.833) > the Shannon-Wiener index (0.735) > substrate richness (0.485) > the AWCD (0.301). The dissipation process of VA was relatively fast and independent of the concentration used. The DT50 values for VA applied at both concentrations were about 16 days. In addition, the dissipation of VA in nsS was three times faster compared to the dissipation of antibiotic in sS. In conclusion, both CLPP and enzyme activities assays appeared to be useful tool for the determination of disturbances within soil microbial communities and used together may be helpful to understand the changes in their catabolic features. The entry of large quantities of VA and/or C. freundii into soil may temporarily change microbial activity thus pose a potential risk for soil functioning.

尽管已有诸多相关研究，但目前学界对于抗生素与耐药菌对土壤微生物群落代谢活性的影响仍认知有限。为明确该影响，本研究在为期90天的实验中，检测了经万古霉素（vancomycin, VA）和/或多重耐药弗氏柠檬酸杆菌（Citrobacter freundii）处理的土壤的群落水平生理剖面（community level physiological profiles, CLPPs）以及选定酶类（脱氢酶、脲酶与磷酸酶）的活性。本研究采用多元分析法与抗性（resistance, RS）/恢复力（resilience, RL）概念，评估本土微生物在暴露于VA和/或高浓度弗氏柠檬酸杆菌时维持其分解代谢活性的潜力。此外，本研究还检测了非灭菌（non-sterile, nsS）与灭菌（sterile, sS）土壤中VA的消解速率。
研究结果显示，在实验第1、15和30天，VA对土壤微生物的代谢活性产生了负面影响：与对照组相比，处理组土壤的CLPP指标值下降了10%~69%，酶活性下降了6%~32%。上述结果表明，土壤微生物对VA和/或弗氏柠檬酸杆菌的初始抗性较低，但从长期来看具备恢复能力。结合抗性指数的平均值，各检测参数的抗性可按以下顺序排序：碱性磷酸酶（0.919）> 酸性磷酸酶（0.899）> 脱氢酶（0.853）> 均匀度指数（0.840）> 脲酶（0.833）> 香农-维纳指数（Shannon-Wiener index, 0.735）> 底物丰富度（0.485）> 平均颜色变化率（Average Well Color Development, AWCD, 0.301）。VA的消解过程相对较快，且与施用浓度无关。两种浓度下VA的DT50值（消解半衰期）均约为16天。此外，非灭菌土壤中VA的消解速率是灭菌土壤的3倍。
综上，群落水平生理剖面与酶活性检测均可作为评估土壤微生物群落扰动的有效手段，二者联合使用有助于解析微生物群落分解代谢特征的变化。大量VA和/或弗氏柠檬酸杆菌进入土壤可能会暂时改变微生物活性，进而对土壤生态系统功能构成潜在风险。