Raman microscopic analysis of single microbial cells.

We demonstrate the utility of the Raman confocal microscope to generate a spectral profile from a single microbial cell and the use of this approach to differentiate bacterial species. In general, profiles from different bacterial taxa shared similar peaks, but the relative abundances of these components varied between different species. The use of multivariate methods subsequently allowed taxa discrimination. Further investigations revealed that the single-cell spectra could be used to differentiate between growth phases of a single species, but these differences did not obscure the overall interspecies discrimination. Finally, we tested the efficacy of the method as a means to identify cells responsible for the uptake of a specific substrate. A single strain was grown in media containing incrementally varying ratios of (13)C(6) to (12)C(6) glucose, and it was found that (13)C incorporation shifted characteristic peaks to lower wavenumbers. These findings suggest that Raman microscopy has significant potential for studies requiring the taxonomic identity and functioning of single microbial cells to be determined.