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. 2020 Sep 3;11:545419. doi: 10.3389/fmicb.2020.545419

FIGURE 1.

FIGURE 1

Fluorescence spectra of B. cereus (A,B), S. aureus (C,D), E. coli (E,F), and S. Typhimurium (G,H). (B,D,F,H) Show the blank and control spectra: bacteria with no dye (colored solid line); peptone water alone (gray solid line); 0.5 μM SYTO 9 in peptone water (gray dashed line); 1.0 μM SYTO 9 in peptone water (gray dotted-dashed line). The spectra shown are recorded from bacterial suspensions with concentrations of approximately 108 CFU/ml bacteria (B. cereus 1.46 × 108; S. aureus 3.49 × 108; E. coli 3.50 × 108; S. Typhimurium 2.46 × 108 CFU/ml). The staining treatment used for these samples was 0 mM EDTA and 15 min staining. Each spectrum shown is the average of duplicate spectra recorded with the specified conditions, and normalized to 1 ms and 1 mW. The peptone water spectrum served as the background spectrum in data analyzes. The background spectrum was not subtracted from the spectra presented here to highlight the minimal difference of the control spectra to blank spectrum.