Positron emission tomography to visualise in-situ microbial metabolism in natural sediments

Positron Emission Tomography simultaneously monitored flow dynamics and in-situ microbial activity in opaque sediment columns. An F-18 labelled electron donor, 2-deoxy-2[F-18]-fluoro-n-glucose ((18)FDG), was added to flowing columns containing sterile sediment, microbially active sediment and quartz sand. 18 FDG accumulated in microbially active, glucose primed, sediment (10(5)-10(6) cells g(-1)) at 10(-16) mol g(-1) (similar to 40% of the 100 MBq spike) giving the first example of 18 FDG uptake by indigenous microorganisms in a complex sediment system at flow rates representative of the shallow subsurface.