Probing bacterial membranes with polarization-resolved second harmonic scattering.

Abstract

For antibiotics that target Gram-positive bacterial cell structures, optimizing their interaction with the cytoplasmic membrane is of paramount importance. Recent time-resolved second harmonic scattering (trSHS) experiments with living bacterial cells have shown that some amphiphilic small molecules display signals consistent with organization within the membrane environment. Such organization could arise, for example, from aggregation, solvent interactions, and/or environmental rigidity. To expand our study of this system, we turn to polarization-resolved SHS (pSHS). PSHS has previously been used with model membranes to extract information about the angular distribution of integrated small molecules. Here we apply pSHS, for the first time, to cells, specifically living Staphylococcus aureus. In doing so, we aim to address contributions ascribed to the organization of amphiphilic molecules in bacterial membranes.