Soil acts as a repository for many metals that human activity releases into the environment. Cadmium enters agricultural soils primarily from application of phosphate fertilizers and sewage sludge. Among soil bacteria, rhizobia have a great agronomic and environmental significance and are major contributors to a sustainable maintenance of soil fertility. However, the services that this group of microorganisms provides are affected by environmental constraints, such as Cd contamination. Bioactive compounds also influence soil microorganisms. Farnesol is a phytocompound with recognized bioactivity, inducing both beneficial and harmful effects. In this study, Rhizobium sp. strain E20-8 was exposed to sole or combined exposure to Cd and farnesol. Results showed that farnesol (25 and 200 µM) did not affect rhizobia; exposure to Cd (µM) inhibited rhizobia growth and induced several biomarkers of oxidative stress; exposure to the combination of farnesol and Cd reduced oxidative damage, and the highest concentration of farnesol tested reduced Cd accumulation and allowed a significant growth recovery. Farnesol protective effects on rhizobia exposed to Cd is novel information which can be used in the development of microbe-based environmental engineering strategies for restoration of metal contaminated areas.

土壤充当人类活动释放到环境中的许多金属的储存库。镉主要通过施用磷肥和污水污泥进入农业土壤。在土壤细菌中，根瘤菌在农业和环境方面具有重要意义，并且是可持续维持土壤肥力的主要因素。但是，这类微生物所提供的服务会受到环境限制（例如Cd污染）的影响。生物活性化合物也会影响土壤微生物。法尼醇是一种具有公认生物活性的植物化合物，可诱导有益和有害作用。在这项研究中，根瘤菌sp。菌株E20-8单独或联合暴露于Cd和法尼醇。结果表明，法呢醇（25和200 µM）不会影响根瘤菌。暴露于Cd（µM）会抑制根瘤菌的生长并诱导多种氧化应激的生物标志物；暴露于法尼醇和Cd的组合可降低氧化损伤，最高浓度的法尼醇可降低Cd的积累并实现显着的生长恢复。法尼醇对暴露于Cd的根瘤菌的保护作用是新颖的信息，可用于开发基于微生物的环境工程策略，以恢复金属污染区域。