ASSAY FOR BACTERIA IN POROUS-MEDIA BY DIFFUSION-WEIGHTED NMR

In this work, an NMR technique capable of detecting bacterial cells an d measuring the cell density in suspension and in porous media has bee n developed, It is based on the pulsed-held-gradient technique and rel ies on the fact that extracellular water diffuses freely while intrace llular water is completely restricted by the relatively impermeable ce ll wall of the bacterium. At high wave vectors, the signal from extrac ellular water is completely suppressed while the signal from intracell ular water is comparatively unaffected. This technique has been applie d to the mapping of bacterial distributions in porous media. This meth od is presented as a nondestructive, real-time technique for biomass c haracterization within laboratory column and flow cell experiments, an d possibly for monitoring in situ bioremediation. (C) 1996 Academic Pr ess, Inc.