The UV-VIS absorption spectra of rhodamine B (brown and orange lines) in the presence of the different concentration of E. coli proteins, respectively, and the UV-VIS absorption spectrum of rhodamine B in the absence of E. coli proteins (pink line).

The concentration of E. coli proteins in the first analyzed sample (brown line) was twice higher than the concentration of E. coli proteins (0.023 g L⁻¹) in the second one (orange line), respectively. The concentration of RB (3.5×10⁻⁴ g L⁻¹) was the same in the all assayed samples.