Department of Biology, West Virginia University, Morgantown, WV, USA.
Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, USA.
Sci Rep. 2021 Sep 29;11(1):19320. doi: 10.1038/s41598-021-97942-9.
Microbial decomposition drives the transformation of plant-derived substrates into microbial products that form stable soil organic matter (SOM). Recent theories have posited that decomposition depends on an interaction between SOM chemistry with microbial diversity and resulting function (e.g., enzymatic capabilities, growth rates). Here, we explicitly test these theories by coupling quantitative stable isotope probing and metabolomics to track the fate of C enriched substrates that vary in chemical composition as they are assimilated by microbes and transformed into new metabolic products in soil. We found that differences in forest nutrient economies (e.g., nutrient cycling, microbial competition) led to arbuscular mycorrhizal (AM) soils harboring greater diversity of fungi and bacteria than ectomycorrhizal (ECM) soils. When incubated with C enriched substrates, substrate type drove shifts in which species were active decomposers and the abundance of metabolic products that were reduced or saturated in the highly diverse AM soils. The decomposition pathways were more static in the less diverse, ECM soil. Importantly, the majority of these shifts were driven by taxa only present in the AM soil suggesting a strong link between microbial identity and their ability to decompose and assimilate substrates. Collectively, these results highlight an important interaction between ecosystem-level processes and microbial diversity; whereby the identity and function of active decomposers impacts the composition of decomposition products that can form stable SOM.
微生物分解作用驱动植物衍生基质转化为微生物产物，这些产物形成稳定的土壤有机物质（SOM）。最近的理论假设，分解作用取决于 SOM 化学性质与微生物多样性及其产生的功能（例如，酶活性、生长速率）之间的相互作用。在这里，我们通过将定量稳定同位素示踪和代谢组学相结合，来跟踪化学组成不同的 C 富集基质的命运，这些基质在被微生物同化并转化为新的土壤代谢产物的过程中会发生变化。我们发现，森林养分经济（例如养分循环、微生物竞争）的差异导致丛枝菌根（AM）土壤比外生菌根（ECM）土壤具有更多样化的真菌和细菌。当用 C 富集基质孵育时，基质类型会导致哪种物种成为活跃的分解者以及代谢产物的丰度发生变化，这些代谢产物在高度多样化的 AM 土壤中被还原或饱和。在微生物多样性较低的 ECM 土壤中，分解途径则更加稳定。重要的是，这些变化中的大多数是由仅存在于 AM 土壤中的类群驱动的，这表明微生物身份与其分解和同化基质的能力之间存在很强的联系。总的来说，这些结果突出了生态系统水平过程和微生物多样性之间的重要相互作用；即活跃分解者的身份和功能会影响可形成稳定 SOM 的分解产物的组成。
