Microorganisms are commonly bonded to various soil minerals, which may influence the redox processes and bacterial metabolism. However, little is known about the impact of particle size of soil minerals on these redox processes in the subsurface environment. In this study, the Cr(VI) bioreduction by Shewanella oneidensis MR-1 (S. oneidensis) was investigated in the presence of various hematite (α-Fe₂O₃) particles with average diameters of 1.0 µm (hem-1 µm) and 80.0 nm (hem-80 nm) under different pH conditions. Fourier transformed infrared spectroscopy coupled with two-dimensional correlation spectroscopy (FTIR-2D-COS) analysis and isothermal titration calorimetry (ITC) were used to explore the interaction between S. oneidensis and hematite and monitor the bacterial metabolic activity, respectively. X-ray photoelectron spectroscopy (XPS) was used to elucidate the Cr(VI) removal mechanisms. Our results showed that 78% of chromate can be reduced to Cr(III) by S. oneidensis alone. Whereas, chromate reduction rates were 62% and 85% in the presence of hem-1 µm and hem-80 nm, respectively. The enhancement of Cr(VI) reduction by S. oneidensis-hem-80 nm complex may be due to the large surface area as well as the positive charge of hem-80 nm at neutral pH, which influences the physical contact between S. oneidensis and iron oxides. The microcalorimetric results showed that both hem-1 µm and hem-80 nm promoted the normal physiological functions of S. oneidensis. XPS confirmed the gradual FeCr₂O₄ formation and Fe(II) depletion during the Cr(VI) reduction process. This work expands our understanding of microbial-mineral interaction and its role in Cr(VI) removal mechanisms in the subsurface environment.

微生物通常与各种土壤矿物质结合，这可能会影响氧化还原过程和细菌代谢。但是，对于地下环境中土壤矿物质的粒径对这些氧化还原过程的影响知之甚少。在这项研究中，将Cr（VI）由生物还原希瓦氏菌oneidensis中MR-1（S. oneidensis中）在各种赤铁矿的存在下进行了研究（的α-Fe ₂ ö ₃）为1.0μm（HEM-1μm）的平均直径的颗粒在不同的pH条件下为80.0 nm（hem-80 nm）。傅立叶变换红外光谱结合二维相关光谱（FTIR-2D-COS）分析和等温滴定热法（ITC）用于研究两者之间的相互作用沙门氏菌和赤铁矿分别监测细菌的代谢活性。X射线光电子能谱（XPS）用于阐明Cr（VI）去除机理。我们的研究结果表明，单独的拟南芥可以将78％的铬酸盐还原为Cr（III）。而在存在hem-1 µm和hem-80 nm的情况下，铬酸盐的还原率分别为62％和85％。铬（VI）还原通过增强S. oneidensis中-hem-80nm的复合物可以是由于大的表面积以及正电荷下摆-80的纳米在中性pH下，其影响之间的物理接触S. oneidensis中和氧化铁。微量热法结果表明，hem-1 µm和hem-80 nm均可促进正常的生理功能。沙门氏菌。XPS证实了在Cr（VI）还原过程中逐渐形成了FeCr ₂ O ₄以及Fe（II）耗尽。这项工作扩大了我们对微生物-矿物质相互作用及其在地下环境中Cr（VI）去除机理中的作用的理解。