Fig. 4
(A-D) Calibration and (E-H) prediction of the PLS model for three offline parameters, based on 2D spectra (A-C, E-G) including and (D, H) excluding the scattered light of H. polymorpha RB11 pC9-FMD (PFMD-GFP) cultivations at eight different phosphate (PO43−) concentrations. This figure is based on the data in Additional file 1: Fig. S7. The PLS models were calibrated with the linearly interpolated values of the filled symbols and a total of 288 2D spectra from the two cultivation conditions shown in A-C. The models in Fig. 4D and H were generated including only the fluorescence intensities. The PLS models for (A, E) glycerol, (B, F) CDW, and (C, D, G, H) pH value were generated using five, five, and three latent variables, respectively. Solid and dotted lines describe the predicted parameter progression of duplicates. Crossed symbols describe the value for the last offline sample taken after 44 h. Cultivation conditions: 48-well microtiter plate with round geometry, modified SYN6-MES medium, liquid volume = 800 μL, shaking diameter = 3 mm, shaking frequency = 1000 rpm, temperature = 30 °C