Terahertz and infrared spectroscopy of bacterial nanofilaments

By means of terahertz and infrared (THz, IR) spectroscopies we have measured the dielectric response of nano-filaments of electrogenic bacteria Shewanella oneidensis MR-1 in a wide frequency and temperature ranges. THz-far-IR spectra are dominated by absorption due to bound water. At helium temperatures and at sub-THz frequencies a boson-peak-like excitation is detected that is typical for disordered materials. The observation is in agreement with the heat capacity measurements.