(681g) Detailed Cellular Phenotype Measurements Using Peptide-Guided Surface Enhanced Raman Scattering (pg-SERS)

A cellular phenotype is determined by its metabolic network and the response of that network to environmental conditions.  This means that both genetic and environmental perturbations can be responsible for altering the chemical composition of a cell.  This has profound implications with microorganisms as we seek to understand the response of cultures to fermentive products (e.g., tolerance to biofuels) and inhibitory substrates.  This is also of considerable interest to understand genetic manipulations designed to engineering higher cellulose content in plants.  Thus, cellular composition is almost never static.  In fact, cellular composition determination involving mass spectroscopy is time consuming, does not consider spatial variation, and is destructive to dynamically responding cultures.  Here, the power of Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) are demonstrated and interfaced with genome-scale modeling for accurate phenotype predictions.  We also demonstrate a new technique of peptide-guided surface enhanced Raman scattering (pg-SERS).  This technique has enabled targeting of specific cellular locations (e.g., the inner cell wall) to study the spatial confined and compartment-specific response of microbial cells to stress.  Specific examples of the response of Escherichia coli K12 to 4-carbon alcohols has revealed distinct responses that are directly related to the length of the hydrophobic chain of the alcohol molecule.  We demonstrate methods of global Raman analysis and more specific functional group targeting using a web-based database made available on our research group website.