Slice, Dice and Analyze Bacteria One Cell and one Atom at a Time

Presented by:
Prof. Radu Popa, Ph.D.
Earth Science
USCAbstract:
Modern microanalysis in material sciences and in environmental sciences is dominated by three technological approaches: Mass Spectrometry (MS), High Resolution Electron Microscopy with EDS (HRTEM-EDS); and Atomic Force Microscopy (AFM). MS instruments have considerable analytical capabilities, yet, cannot probe samples at very small scales (such as 1 m); and thus are less helpful in studying individual microbes. HRTEM-EDS and AFM instruments can reveal structures at Angstrom scales but have considerable analytical limitations. Nano-Secondary Ion Mass Spectrometry (NanoSIMS) is an edge technology; an ion microprobe developed for the purpose of bringing together the benefits of high resolution imaging with the analytical capabilities of MS. Using NanoSIMS it is now possible to explore the chemistry and the isotopic composition of one bacterium cell, with 50 nm lateral resolution and 10-20 Å vertical resolution. We tested the limits of this technology by addressing physiological questions in individual microbes. The model organisms for this study are Cyanobacteria, a group of Prokaryotes with an impressive array of metabolic capabilities including N2-fixation, C-fixation and heterotrophy. In some filaments of Cyanobacteria such as Anabaena sp. certain cells named heterocysts are metabolically specialized. This specialization results in considerable biochemical differences between adjacent cells. We used NanoSIMS to measure this variability and to make kinetic analyses bacteria. Currently, NanoSIMS allows the physiologist study the metabolic performance of one microbe, and the micropaleontologist to distinguish abiotic from biogenic structures in ancient samples. In the near future ion microprobe instruments will also be used for chemical and isotopic characterization of samples in environmental studies, in astrobiology and in forensic analysis.

Location: Kaprielian Hall (KAP) - 156

Audiences: Everyone Is Invited

Contact: Evangeline Reyes