Research Unit Comparative Microbiome Analysis - Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764, Neuherberg, Germany.
Chair for Soil Ecology - Technische Universität München, Ingolstädter Landstr. 1, 85764, Neuherberg, Germany.
Sci Rep. 2019 Feb 19;9(1):2280. doi: 10.1038/s41598-018-38147-5.
The frequency of extreme drought and heavy rain events during the vegetation period will increase in Central Europe according to future climate change scenarios, which will affect the functioning of terrestrial ecosystems in multiple ways. In this study, we simulated an extreme drought event (40 days) at two different vegetation periods (spring and summer) to investigate season-related effects of drought and subsequent rewetting on nitrifiers and denitrifiers in a grassland soil. Abundance of the microbial groups of interest was assessed by quantification of functional genes (amoA, nirS/nirK and nosZ) via quantitative real-time PCR. Additionally, the diversity of ammonia-oxidizing archaea was determined based on fingerprinting of the archaeal amoA gene. Overall, the different time points of simulated drought and rewetting strongly influenced the obtained response pattern of microbial communities involved in N turnover as well as soil ammonium and nitrate dynamics. In spring, gene abundance of nirS was irreversible reduced after drought whereas nirK and nosZ remained unaffected. Furthermore, community composition of ammonia-oxidizing archaea was altered by subsequent rewetting although amoA gene abundance remained constant. In contrast, no drought/rewetting effects on functional gene abundance or diversity pattern of nitrifying archaea were observed in summer. Our results showed (I) high seasonal dependency of microbial community responses to extreme events, indicating a strong influence of plant-derived factors like vegetation stage and plant community composition and consequently close plant-microbe interactions and (II) remarkable resistance and/or resilience of functional microbial groups involved in nitrogen cycling to extreme weather events what might indicate that microbes in a silty soil are better adapted to stress situations as expected.
根据未来气候变化情景，中欧地区植被生长期极端干旱和暴雨事件的发生频率将会增加，这将对陆地生态系统的多种功能产生影响。在本研究中，我们模拟了两个不同植被期（春季和夏季）的一次极端干旱事件（40 天），以研究干旱及其随后复水对草地土壤中硝化菌和反硝化菌的季节相关影响。通过定量实时 PCR 对功能基因（amoA、nirS/nirK 和 nosZ）进行定量，评估了感兴趣的微生物群体的丰度。此外，基于古菌 amoA 基因指纹图谱，确定了氨氧化古菌的多样性。总的来说，模拟干旱和复水的不同时间点强烈影响了参与氮转化以及土壤铵和硝酸盐动态的微生物群落的获得响应模式。在春季，干旱后nirS 的基因丰度不可逆转地降低，而 nirK 和 nosZ 不受影响。此外，尽管 amoA 基因丰度保持不变，但随后的复水改变了氨氧化古菌的群落组成。相比之下，在夏季，硝化古菌的功能基因丰度或多样性模式没有受到干旱/复水的影响。我们的研究结果表明：（I）微生物群落对极端事件的响应具有很强的季节性依赖性，表明植物衍生因素（如植被阶段和植物群落组成）对其具有强烈影响，因此植物-微生物相互作用密切；（II）参与氮循环的功能微生物群体对极端天气事件具有显著的抵抗力和/或恢复力，这可能表明人们期望在粉质土壤中的微生物对胁迫情况具有更好的适应性。
