Microbial biofilm has been found to impact the mobility of nanoparticles in saturated porous media by altering physicochemical properties of collector surface. However, little is known about the influence of biofilm’s biological activity on nanoparticle transport and retention. Here, the transport of ferrihydrite nanoparticles (FhNPs) was studied in quartz sands coated with biofilm of Shewanella oneidensis MR-1 that is capable of reducing Fe(III) through extracellular electron transfer (EET). It was found that MR-1 biofilm coating enhanced FhNPs’ deposition under different pH/ionic strength conditions and humic acid concentrations. More importantly, when the influent electron donor (glucose) concentration was increased to promote biofilm’s EET activity, the breakthrough of FhNPs in biofilm-coated sands was inhibited. A lack of continuous and stable supply of electron donor, on the contrary, led to remobilization and release of the originally retained FhNPs. Column experiments with biofilm of EET-deficient MR-1 mutants (ΔomcA/ΔmtrC and ΔcymA) further indicated that the impairment of EET activity decreased the retention of FhNPs. It is proposed that the effective surface binding and adhesion of FhNPs that is required by direct EET cannot be neglected when evaluating the transport of FhNPs in sands coated with electroactive biofilm.

已经发现微生物生物膜通过改变收集器表面的理化性质来影响纳米颗粒在饱和多孔介质中的迁移率。然而，关于生物膜的生物活性对纳米颗粒运输和保留的影响知之甚少。在这里，研究了在Shewanella oneidensis生物膜覆盖的石英砂中水铁矿纳米颗粒（FhNPs）的传输。能够通过细胞外电子转移（EET）还原Fe（III）的MR-1。发现在不同的pH /离子强度条件和腐殖酸浓度下，MR-1生物膜涂层增强了FhNPs的沉积。更重要的是，当增加流入的电子供体（葡萄糖）浓度以促进生物膜的EET活性时，FhNPs在生物膜涂层砂中的渗透受到抑制。相反，缺乏连续稳定的电子供体供应导致最初保留的FhNPs迁移和释放。EEE缺陷MR-1突变体（ΔomcA / ΔmtrC和ΔcymA）生物膜的柱实验）进一步表明，EET活性受损会降低FhNPs的保留。有人提出，当评估FhNPs在涂有电活性生物膜的沙土中的迁移时，不能忽略直接EET所要求的FhNPs的有效表面结合和粘附。