Partitioning of Prokaryotic Functional Diversity under Different Land Use

该项目的目的是阐明土壤细菌的主要群体(酸性细菌、放线细菌、甲型蛋白细菌)、植物群落、土壤因素以及探索区土地利用之间的耦合。研究将集中在(1)活跃的根际细菌与植物之间的功能耦合动态，(2)单个细菌在降解植物分泌物、植物凋落物和动物遗骸中的特定功能，以及(3)在探索实验室中根际和土壤微生物群落的时间稳定性。通过捕获RNA同位素探测(CARIP)对根分泌物进行时间分辨的13C稳定同位素脉冲标记，并将分泌物的组成与高通量测序确定的细菌群落的组成相关联，将阐明单个细菌物种在有机碳通量中的功能耦合。细菌的个体功能作用将通过摄取13C标记的底物，随后通过稳定同位素RNA探测(SIP)鉴定活性种型，以及通过元基因组学和元翻译组学来测试。应研究这些细菌群落对土地利用的年内变异性。最后，将通过对跨越6年的三个样本组的Illumina序列分析，对所有300个试验田的长期影响进行评估，这将提供机会来阐明细菌群落的长期变化，并将它们与环境变量和土地利用的变化联系起来。

The aim of the project is to elucidate the coupling between major groups of soil bacteria (Acidobacteria, Actinobacteria, Alphaproteobacteria), plant communities, edaphic factors, as well as land use in the Exploratories. Investigations will focus on (1) the dynamics of functional coupling between active rhizosphere bacteria and plants, (2) specific functions of individual bacteria in the degradation of plant exudates, plant litter, and animal remains, as well as (3) the time dependent stability of rhizosphere and bulk soil microbial communities in the Exploratories. The functional coupling of individual bacterial species in organic carbon flux will be elucidated through time resolved 13C-stable isotope pulse labeling of root exudates using Captured RNA Isotope Probing (CARIP), and correlating the composition of exsudates with that of bacterial communities determined by high throughput sequencing. Individual functional roles of bacteria will be tested by the uptake of 13C-labelled substrates with subsequent identification of active phylotypes by stable isotope probing of RNA (SIP), and by metagenomics and metatranscriptomics. Intra-annual variability of these bacterial communities in response to land use shall be studied. Finally, long-term effects will be assessed across all 300 experimental plots by Illumina sequence analysis of three sample sets spanning 6 years, which provides the opportunity to elucidate long-term changes in bacterial communities and relating them to changes in environmental variables and land use.