As H V, Lens P
Wageningen NMR Centre and Laboratory of Molecular Physics, Wageningen University, The Netherlands.
J Ind Microbiol Biotechnol. 2001 Jan-Feb;26(1-2):43-52.
The operation of bioreactors and the metabolism of microorganisms in biofilms or soil/sediment systems are strongly dictated by the transport processes therein. Nuclear magnetic resonance (NMR) spectroscopy or magnetic resonance imaging (MRI) allow nondestructive and noninvasive quantification and visualisation (in case of MRI) of both static and dynamic water transport phenomena. Flow, mass transfer and transport processes can be measured by mapping the (proton) displacement in a defined time interval directly in a so-called pulsed field gradient (PFG) experiment. Other methods follow the local intensity in time-controlled sequential images of water or labelled molecules, or map the effect of contrast agents. Combining transport measurements with relaxation-time information allows the discrimination of transport processes in different environments or of different fluids, even within a single picture element in an image of the porous biosystem under study. By proper choice of the applied NMR method, a time window ranging from milliseconds to weeks (or longer) can be covered. In this paper, we present an overview of the principles of NMR and MRI techniques to visualise and unravel complex, heterogeneous transport processes in porous biological systems. Applications and limitations will be discussed, based on results obtained in (model) biofilms, bioreactors, microbial mats and sediments.
生物反应器的运行以及生物膜或土壤/沉积物系统中微生物的代谢，在很大程度上取决于其中的传输过程。核磁共振（NMR）光谱或磁共振成像（MRI）能够对静态和动态水传输现象进行无损、非侵入式的定量分析以及可视化（对于MRI而言）。流动、传质和传输过程可以通过在所谓的脉冲场梯度（PFG）实验中直接绘制在定义的时间间隔内（质子）位移来测量。其他方法则是跟踪水或标记分子在时间控制的序列图像中的局部强度，或者绘制造影剂的效果。将传输测量与弛豫时间信息相结合，可以区分不同环境或不同流体中的传输过程，甚至在正在研究的多孔生物系统图像中的单个像素内也能做到。通过适当选择应用的NMR方法，可以覆盖从毫秒到数周（或更长）的时间窗口。在本文中，我们概述了NMR和MRI技术的原理，以可视化和揭示多孔生物系统中复杂的、非均匀的传输过程。将基于在（模型）生物膜、生物反应器、微生物垫和沉积物中获得的结果，讨论其应用和局限性。
