Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), State Key Laboratory for Biocontrol, Sun Yat-sen University, Guangzhou 510006, China.
College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
Environ Sci Technol. 2022 Jun 21;56(12):9052-9062. doi: 10.1021/acs.est.1c08069. Epub 2022 May 11.
Soil protists are essential but often overlooked in soil and could impact microbially driven element cycling in natural ecosystems. However, how protists influence heavy metal cycling in soil remains poorly understood. In this study, we used a model protist, , to explore the effect of interactions between soil amoeba and metal-reducing bacteria on the reduction of soil Fe(III) and Cr(VI). We found that could preferentially prey on the Fe(III)-reducing bacterium S12 and significantly decrease its biomass. Surprisingly, this predation pressure also stimulated the activity of a single S12 bacterium to reduce Fe(III) by enhancing the content of electron-transfer protein cyt , intracellular ATP synthesis, and reactive oxygen species (e.g., HO). We also found that could not prey on the Cr(VI)-reducing bacterium . In contrast, became edible to amoebae in the presence of S12, and their Cr(VI) reduction ability decreased under amoeba predation pressure. This study provides direct evidence that protists can affect the Cr and Fe cycling via the elective predation pressure on the metal-reducing bacteria, broadening our horizons of predation of protists on soil metal cycling.
土壤原生动物是土壤中必不可少但经常被忽视的一部分，它们可能会影响微生物驱动的自然生态系统中元素的循环。然而，原生动物如何影响土壤中重金属的循环仍知之甚少。在这项研究中，我们使用了一种模式原生动物 ，来探索土壤变形虫与金属还原菌之间的相互作用对土壤 Fe(III)和 Cr(VI)还原的影响。我们发现 可以优先捕食 Fe(III)还原菌 S12，并显著降低其生物量。令人惊讶的是，这种捕食压力还通过增强电子转移蛋白 cyt 的含量、细胞内 ATP 的合成和活性氧物质（如 HO）来刺激单个 S12 细菌还原 Fe(III)的活性。我们还发现 不能捕食 Cr(VI)还原菌 。相反，在 S12 的存在下， 对变形虫变得可食，并且在变形虫捕食压力下，它们的 Cr(VI)还原能力下降。本研究提供了直接证据，证明原生动物可以通过对金属还原菌的选择性捕食压力来影响 Cr 和 Fe 的循环，拓宽了我们对原生动物捕食土壤金属循环的认识。
