Fig. 2: Biophysical signatures of nucleic acids are consistent with those of the eDNA fibres and are preserved when isolated.
Representative circular dichroism (CD) spectra (n = 2) of A P. aeruginosa biofilm and B eDNA gel isolate at 30 °C (green), 40 °C (blue), 60 °C (red) and 95 °C (black). C Rolling average in amplitude (of five data points) around the mean of dominant NA peak, CDmax (260–285 nm), from CD spectra of P. aeruginosa biofilm (seen in A) and its extracted extracellular nucleic acid gel (i.e. isolate; seen in B) from T = 30 to 95 °C. Error bars refer to the standard deviation of the rolling averages. D Representative CD spectra of P. aeruginosa biofilm cDNA at 30 °C (green), 40 °C (blue), 60 °C (red) and 95 °C (black). E Rolling average in amplitude (of five data points) around the mean amplitude of dominant NA peak, CDmax (260–285 nm), from CD spectra of P. aeruginosa biofilm cDNA (seen in D) from T = 30 to 95 °C with and without solubilisation in 1-ethyl-3-methylimidazolium and fractional precipitation. Error bars refer to the standard deviation of the rolling averages. Confocal micrograph of 3-day static P. aeruginosa wild-type biofilm with no pre-heating (F), with pre-heating to 60 °C (G) and pre-heating to 70 °C (H) showing eDNA fibres in the matrix of the biofilm, illustrated by binding to DNA-specific dye propidium iodide (red), that partially and completely disappear upon heating to 60 and 70 °C, respectively. Scale bars represent 10 µm.
