Resonance Raman spectra of Hemin (A), OmcA (B), MtrC (C), and SERS of cell outer surface of wild type MR-1. Although the Raman intensity shows fluctuation, the typical vibrational modes, such as ν4, ν3, ν2, and ν10, are obvious. Based on the similarity of B, C, and D, protein OmcA and MtrC are identified to be the main compositions of the outer membrane of MR-1, which is consistent with the previous reports.18