Fig. 3

Bioburden and predicted toxin accumulation in bacteria. A A. tumefaciens bioburden during the infiltration, optional blanching, extraction and clarification of N. benthamiana biomass and in the corresponding process intermediates. The CFU per area (air and surface samples) or per liter of process intermediate was assessed on selective and non-selective (air samples only) YEB agar plates. B Samples as in A but with the CFU [L⁻¹] count converted to an equivalent OD_600nm [–] using a conversion factor of 6.99 × 10⁻¹³ [L] based on a published correlation [50]. C Correlation between DsRed and IgG1 accumulation in plants and E. coli (Pearson’s r = 0.99, R² = 0.99) with an average correlation factor (slope) of 0.43. D Correlation between DsRed and IgG1 accumulation in tobacco BY-2 PCPs and A. tumefaciens (Pearson’s r = 0.99, R² = 0.96) with an average correlation factor of 0.03. DsRed and IgG1 accumulation in E. coli and A. tumefaciens were measured by ELISA (Fig. 2C, D). Data are means ± SD (n = 4–21 data points depending on the sample). CFU—colony forming unit; DM—dry mass; n.a.—not applicable; OD—optical density