Medical Department Seminar

Understanding single cell environmental microbiology is a key challenge in fields ranging from medicine to biofuel development to C sequestration. Isotope-labeling experiments provide a useful means to investigate the ecophysiology of microbes in the environment and allow measurement of nutrient transfers between cell types, symbionts and consortia. The combination of Nano-Secondary Ion Mass Spectrometry (NanoSIMS) analysis, in situ labeling and high resolution microscopy allows isotopic analysis to be linked to phylogeny and morphology and holds great promise for fine-scale studies of microbial systems. In NanoSIMS analysis, samples are sputtered with an energetic primary beam (Cs+, O-) liberating secondary ions that are separated by the mass spectrometer and detected in a suite of electron multipliers. Five isotopic species may be analyzed concurrently with spatial resolution as fine as 50nm. A high sensitivity isotope ratio "map" can then be generated for the analyzed area. NanoSIMS analyses are particularly powerful when used in combination with analysis techniques such as TEM, STXM, CARD-FISH and high density oligonucleotide microarrays. These newly developed approaches provide correlated oligonucleotide, enzymatic and metabolic image data and can help unravel the metabolic processes of complex microbial communities in soils, biofilms and aquatic systems.