Magnetic resonance imaging of structure, diffusivity, and copper immobilization in a phototrophic biofilm
Magnetic resonance imaging of structure, diffusivity, and copper immobilization in a phototrophic biofilm
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DOI：
10.1128/aem.02783-07
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发表时间：
2008-08-01
影响因子：
4.4
通讯作者：
Holmes, W. M.
中科院分区：
文献类型：
--
作者：
Phoenix, V. R.;Holmes, W. M.
磁共振成像（MRI）被用来空间解析的结构，水扩散，铜运输的光养生物膜及其命运。MRI能够解决相当大的结构异质性，从经典的层状结构类似于500 μ m厚的结构，没有明显的排序。脉冲场梯度（PFG）分析空间分辨水扩散系数，表现出相对较小或无衰减（扩散系数范围为1.7 X 10（-9）m（2）s（-1）至2.2 X 10（-9）m（2）s（-1））。然后将生物膜与10 mg/L Cu（2+）溶液反应，并使用横向参数图在空间和时间上映射生物膜内的铜固定。值得注意的是，类似于生物医学研究中使用的校准协议成功地量化了整个生物膜中的铜浓度。Cu浓度的变化受生物膜结构的控制。铜的固定化在最初的20至30小时内是最快的（类似于5毫克铜升（-1）小时（-1）），然后在实验的剩余60小时内慢得多。金属在生物膜内的运输受扩散和固定控制。这是探索使用Bartlett和Gardner模型，通过一个假设的膜表现出类似的光养生物膜的属性检查扩散和吸附。较高的吸附常数（K）导致较长的滞后时间，直到开始固定在深度，但较高的实际吸附速率。MRI和反应传输模型是通用的工具，可以显着提高我们的理解，在自然发生的生物膜中的重金属固定。
Magnetic resonance imaging (MRI) was used to spatially resolve the structure, water diffusion, and copper transport of a phototrophic biofilm and its fate. MRI was able to resolve considerable structural heterogeneity, ranging from classical laminations similar to 500 mu m thick to structures with no apparent ordering. Pulsed-field gradient (PFG) analysis spatially resolved water diffusion coefficients which exhibited relatively little or no attenuation (diffusion coefficients ranged from 1.7 X 10(-9) m(2) s(-1) to 2.2 X 10(-9) m(2) s(-1)). The biofilm was then reacted with a 10-mg liter(-1) Cu(2+) solution, and transverse-parameter maps were used to spatially and temporally map copper immobilization within the biofilm. Significantly, a calibration protocol similar to that used in biomedical research successfully quantified copper concentrations throughout the biofilm. Variations in Cu concentrations were controlled by the biofilm structure. Copper immobilization was most rapid (similar to 5 mg Cu liter(-1) h(-1)) over the first 20 to 30 h and then much slower for the remaining 60 h of the experiment. The transport of metal within the biofilm is controlled by both diffusion and immobilization. This was explored using a Bartlett and Gardner model which examined both diffusion and adsorption through a hypothetical film exhibiting properties similar to those of the phototrophic biofilm. Higher adsorption constants (K) resulted in longer lag times until the onset of immobilization at depth but higher actual adsorption rates. MRI and reaction transport models are versatile tools which can significantly improve our understanding of heavy metal immobilization in naturally occurring biofilms.