Partitioning of Prokaryotic Functional Diversity under Different Land Use

该项目的目的是阐明主要土壤细菌群（酸杆菌、放线菌、阿尔法变形菌）、植物群落、土壤因子以及探索区土地利用之间的耦合关系。调查将集中在(1)活性根际细菌与植物之间功能耦合的动态，(2)单个细菌在植物渗出物，植物凋落物和动物遗骸降解中的特定功能，以及(3)根际和土壤微生物群落的时间依赖性稳定性。利用捕获RNA同位素探针（CARIP）对根分泌物进行时间分辨13c稳定同位素脉冲标记，并将分泌物组成与高通量测序确定的细菌群落组成相关联，从而阐明有机碳通量中单个细菌物种的功能耦合。细菌的个体功能作用将通过摄取13c标记的底物进行测试，随后通过RNA稳定同位素探测（SIP）以及宏基因组学和亚转录组学鉴定活性种型。应研究这些细菌群落随土地利用的年际变化。最后，将通过Illumina序列分析对所有300个实验地块进行为期6年的长期影响评估，这将为阐明细菌群落的长期变化以及它们与环境变量和土地利用变化的关系提供机会。

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.