Soil Fertilization Leads to a Decline in Between-Samples Variability of Microbial Community δ13C Profiles in a Grassland Fertilization Experiment
Soil Fertilization Leads to a Decline in Between-Samples Variability of Microbial Community δ13C Profiles in a Grassland Fertilization Experiment
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土壤施肥导致草地施肥实验中微生物群落 δ13C 谱的样本间变异性下降
作者：
S. Veresoglou;B. Thornton;G. Menexes;A. Mamolos;D. S. Veresoglou
采用气相色谱-燃烧同位素比值质谱法（GC-C-IRMS）测定了希腊北方温带草原氮（N）和磷（P）因子施肥试验中天然丰度水平下PLFAs的13 C/12 C比值。在每个地块中，两个根际样品来自集中在个别剪股颖和夏枯草植物。据推测，优先以腐殖酸凋落物（如真菌）为食的微生物的同位素信号将被受精作用比使用不稳定C.土壤微生物群落δ 13 C受磷、氮施肥制度和植物种类的影响。然而，与我们最初的假设相反，当单独分析时，我们无法检测到营养对单个微生物组的显著影响。治疗内的变异性，从哈特利的F最大值测试中的五个第一PCA组件轴，以及在PCA记分图和Mahalanobis距离的凸包的大小进行评价，是相当高的非受精对照。此外，一个显着的关系建立在PLFA丰度的变化和各自的变化之间的δ 13 C的样品和那些同时施肥与N和P。我们的结论是，在没有标记的情况下使用化合物的特定同位素分析是一个有价值的和被忽视的工具，在获得洞察微生物群落功能。
Gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) was used to measure the 13C/12C ratios of PLFAs at natural abundance levels from a temperate grassland nitrogen (N) and phosphorus (P) factorial fertilization experiment in northern Greece. In each plot two rhizosphere samples were derived centred around individual Agrostis capillaris and Prunella vulgaris plants. It was hypothesized that the isotopic signal of microbes that preferentially feed on recalcitrant litter such as fungi would be modified by fertilization more strongly than that of opportunistic microbes using labile C. Microbial community δ13C was affected by both P and N fertilization regime and plant species identity. However, we have been unable to detect significant nutrient effects on individual groups of microbes when analyzed separately in contrast to our original hypothesis. Intra-treatment variability, as evaluated from Hartley’s F max tests in the five first PCA components axes as well as the size of the convex hulls in PCA scoreplots and Mahalanobis distances, was considerably higher in the non-fertilized controls. Moreover, a significant relationship was established between the change in PLFA abundances and their respective changes in δ13C for the aggregate of samples and those simultaneously fertilized with N and P. We conclude that use of compound specific isotope analysis in the absence of labelling represents a valuable and overlooked tool in obtaining an insight of microbial community functioning.