Phenolic compounds perform various functions in soil ranging from microbial substrate to toxin and form the basis of several plant-mediated processes. The aim of this study was to investigate how phenolics commonly exuded by tree roots influence soil organic matter (SOM) decomposition and interact with other labile forms of carbon (C) abundant in root exudates. Therefore, we performed a 38-day incubation experiment and assessed whether phenolic compounds (benzoic acid, caffeic acid and catechin) facilitated or inhibited SOM decomposition in a glucose-amended forest soil. Changes in decomposition, substrate use, fungal and bacterial community composition, and microbial abundance and activity were measured over time using ¹³C-stable-isotope tracing, DNA-based molecular methods and enzyme assays. Our findings showed that phenolics inhibited microbial activity and abundance to varying degrees. Yet, benzoic acid was the only compound producing a substantial priming effect leading to a 21% increase in SOM decomposition, which was amplified in glucose-amended soils. This stimulation in microbial activity was associated with an increase in β-1,4-glucosidase activity and the bacterial genera Paraburkholderia and Caballeronia of the Burkholderiaceae family. Phenolics drove microbial community shifts in glucose-amended soils with negligible interactive effects. In conclusion, phenolic priming of SOM decomposition is associated with microbial community shifts and amplified in the presence of glucose. This evidence emphasizes the need for considering phenolics and interactions among root exudates as priming mechanisms in the rhizosphere and other soil environments where aromatics and phenolic compounds are abundant.

酚类化合物在土壤中发挥多种功能，从微生物底物到毒素，并构成多种植物介导过程的基础。这项研究的目的是调查通常由树根分泌的酚类物质如何影响土壤有机质（SOM）分解并与根分泌物中大量的其他不稳定形式的碳（C）相互作用。因此，我们进行了38天的培养实验，评估了酚类化合物（苯甲酸，咖啡酸和儿茶素）是否在葡萄糖改良的森林土壤中促进或抑制了SOM分解。使用¹³测量了随时间变化的分解，底物使用，真菌和细菌群落组成以及微生物丰度和活性的变化。C稳定同位素示踪，基于DNA的分子方法和酶测定。我们的发现表明，酚类药物在不同程度上抑制了微生物的活性和丰度。但是，苯甲酸是唯一一种产生大量引发作用的化合物，可导致SOM分解增加21％，这在葡萄糖修饰的土壤中被放大。这种微生物活性的刺激与β-1,4-葡糖苷酶活性的增加以及细菌属抛物线虫和Caballeronia有关Burkholderiaceae家族。酚类物质在葡萄糖修饰的土壤中推动了微生物群落的迁移，而相互作用的影响可忽略不计。总之，SOM分解的酚类引发与微生物群落转移有关，并在葡萄糖存在下被放大。该证据强调需要在根际和芳香烃和酚类化合物含量丰富的其他土壤环境中考虑酚和根系分泌物之间的相互作用作为引发机制。