METABOLIC SPATIAL VARIABILITY IN ELECTRODE-RESPIRING GEOBACTER SULFURREDUCENS BIOFILMS.
METABOLIC SPATIAL VARIABILITY IN ELECTRODE-RESPIRING GEOBACTER SULFURREDUCENS BIOFILMS.
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DOI：
10.1039/c3ee40203g
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发表时间：
2013-06-01
影响因子：
32.5
通讯作者：
Beyenal H
中科院分区：
文献类型：
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作者：
Renslow R;Babauta J;Dohnalkova A;Boyanov M;Kemner K;Majors P;Fredrickson J;Beyenal H
在这项研究中，我们使用电化学-核磁共振生物膜反应器对硫还原地杆菌生物膜的电子传递速率、电子供体深度分布和生物膜结构进行了量化。我们的目标是确定在电极呼吸硫还原菌生物膜的电子传递过程中是否存在电子供体限制。靠近生物膜顶部的细胞消耗醋酸盐并在代谢上活跃；然而，在生物膜顶部100微米内，醋酸盐浓度降至低于检测到的水平。此外，电极表面附近生物膜的孔隙率降至10%以下，加剧了较低区域对醋酸盐的排斥。醋酸盐贫乏区域中致密的生物膜基质起到了将生物膜顶部产生的电子传递到电极上的电气管道的作用。为了验证细胞代谢活性的分布，我们使用铀作为氧化还原活性探针来定位电子转移活性，并使用X射线吸收光谱来确定铀的氧化状态。靠近顶部的细胞比靠近底部的细胞更能有效地减少UVI。高分辨率的电子显微镜图像显示，靠近顶部的是完整的、健康的细胞，而靠近底部的是质壁细胞。与文献中提出的假设最接近电极表面的细胞由于较低的电子转移阻力而代谢最活跃的模型相反，我们的结果表明通过生物膜的阻力不会限制远程电子转移。远离电极的细胞可以通过代谢不活跃的细胞呼吸，利用它们在初始生物膜形成过程中产生的细胞外基础设施。
In this study, we quantified electron transfer rates, depth profiles of electron donor, and biofilm structure of Geobacter sulfurreducens biofilms using an electrochemical-nuclear magnetic resonance microimaging biofilm reactor. Our goal was to determine whether electron donor limitations existed in electron transfer processes of electrode-respiring G. sulfurreducens biofilms. Cells near the top of the biofilms consumed acetate and were metabolically active; however, acetate concentration decreased to below detection within the top 100 microns of the biofilms. Additionally, porosity in the biofilms fell below 10% near the electrode surface, exacerbating exclusion of acetate from the lower regions. The dense biofilm matrix in the acetate-depleted zone acted as an electrical conduit passing electrons generated at the top of the biofilm to the electrode. To verify the distribution of cell metabolic activity, we used uranium as a redox-active probe for localizing electron transfer activity and X-ray absorption spectroscopy to determine the uranium oxidation state. Cells near the top reduced UVI more actively than the cells near the base. High-resolution transmission electron microscopy images showed intact, healthy cells near the top and plasmolyzed cells near the base. Contrary to models proposed in the literature, which hypothesize that cells nearest the electrode surface are the most metabolically active because of a lower electron transfer resistance, our results suggest that electrical resistance through the biofilm does not restrict long-range electron transfer. Cells far from the electrode can respire across metabolically inactive cells, taking advantage of their extracellular infrastructure produced during the initial biofilm formation.