X射线对我国两种典型土壤中微生物活性及群落结构的影响

Effect of X-ray micro-computed tomography on the metabolic activity and diversity of soil microbial communities in two Chinese soils

摘要:

【目的】 X射线断层扫描技术(X-ray micro-Computed Tomography, micro-CT)能够原位、无损伤的解析土壤物理结构,有望与土壤微生物研究结合,以有助于更好的了解土壤生态系统。由于土壤的高度异质性, X射线扫描和土壤微生物分析应为同一样品,但是关于X射线扫描后的土壤样品是否兼容土壤微生物分析却鲜有报道,即X射线扫描是否影响土壤微生物的活性及群落尚未明确。【方法】本研究采集我国华北地区潮土和亚热带红壤,利用平板计数、微量热技术和高通量测序技术研究了X射线扫描对可培养微生物数量、土壤微生物的代谢热和群落结构的影响。【结果】 X射线辐射显著降低了2种土壤中活体细菌的数量,同时微生物的代谢活性也发生改变;在分子水平上,基于细菌16S rRNA基因的高通量数据显示2种土壤的细菌多样性指数发生了变化,而其群落结构均无改变。【结论】 X射线断层扫描技术并不兼容土壤微生物功能的研究;但可兼容基于分子生物学的微生物群落结构分析。

Abstract:

[Objective] X-ray micro-computed tomography(micro-CT) technology, as used in the in situ and nondestructive analysis of soil physical structure, provides the opportunity of associating soil physical and biological assays. Due to the high heterogeneity of the soil matrix, X-ray micro-CT scanning and soil microbial assays should be conducted on the same soil sample. This raises the question whether X-ray micro-CT influences microbial function and diversity of the sample soil to be analyzed.[Methods] To address this question, we used plate counting, microcalorimetry and pyrosequencing approaches to evaluate the effect of X-ray-at doses typically used in micro-CT-on soil microorganisms in a typical soil of North China Plain, Fluvo-aquic soil and in a typical soil of subtropical China, Ultisol soil, respectively.[Results] In both soils radiation decreased the number of viable soil bacteria and disturbed their thermogenic profiles. At DNA level, pyrosequencing revealed that alpha diversities of two soils biota were influenced in opposite ways, while beta diversity was not affected although the relative abundances of some guilds were changed.[Conclusion] These findings indicate that the metabolically active aspects of soil biota are not compatible with X-ray micro-CT; while the beta molecular diversity based on pyrosequencing could be compatible.