Table 1.
Strains used for FTIR phenotyping study.
Fig 1.
The workflow of sample preparation and high-throughput screening FTIR spectroscopy is shown.
In the first step strains were cultivated for 24 or 48 hours in a Bioscreen C microcultivation instrument. Then samples are transferred to a 96-well plate for washing. Washing is performed in WellWash AC microtiter plate washer. At the last step, samples are re-suspended and a film of 8 μl suspension is applied to the FTIR plates. Finally spectra are measured using a Bruker Tensor 27 spectrometer with an eXTension (HTS-XT) unit. The measurement time is approximately 3 hours per plate.
Fig 2.
SEM images of films used for FTIR micro-spectroscopy are shown.
In (a) and (b) the intact films of strain 19 and the wild type are shown, respectively. In (c) a deficient film formed by a suspension of cells of strain 24 is shown, revealing that the film consists of approximately 8 layers.
Fig 3.
The first and the second scores of the PCA of time measurements of a selection of yeast knock-out strains are shown in (a) and (b), respectively.
Samples are measured after 10, 12, 15, 18, 21, 24, 36, 48, 60, and 72 hours. The numbers of the strains are given in the legends.
Table 2.
Variability within technical and biological replicates of S. cerevisiae wt. Variability within yeast strains, species and genera.
Fig 4.
The first and the second scores of the PCA of one experimental run are shown for two harvest time points and two spectral regions.
In (a) and (b) the score plots are shown for the spectral region 2800 cm-1–3100 cm-1 for harvest times 24 hours and 48 hours, respectively. In (c) and (d) the score plots are shown for the spectral region 900–1800 cm-1 for harvest times 24 hours and 48 hours, respectively.
Table 3.
Strains used for FTIR phenotyping study and GC.
Fig 5.
The first and the second scores of both experimental runs are shown for strains harvested after 48 hours for the spectral regions 2800–3100 cm-1 and 900–1800 cm-1, in (a) and (b), respectively.
The principal component model is built on the data collected in run 1for the fatty acid region (2800–3100 cm-1) and the region 900–1800 cm-1, in (a) and (b) respectively. The data of run two is projected into these models.
Table 4.
GC results for total fatty acids.*
Table 5.
GC results for phosphatidylcholine.*
Table 6.
GC results for phosphatidylethanolamine.*
Fig 6.
The parallel GC and FTIR results of a selection of samples grown in Erlenmeyer flasks are shown.
(a) The experimental run to run variability for the ratio of saturated versus monounsaturated fatty acids is shown. Data are plotted as a scatter plot, where the first experimental run is plotted on the x-axis and the second experimental run is plotted on the y-axis. (b) The first and the second scores of the PCA of the GC analyses are shown. (c) The correlation loading plot corresponding the PCA of the GC analyses is shown (d) The first and the second scores of the PCA of the fatty acid region (2800–3100 cm-1) of the FTIR analysis are shown.
Table 7.
Prediction results.
Fig 7.
The prediction results for the prediction of GC fatty acids by FTIR data are shown.
(a) The predicted ratio of saturated and monounsaturated fatty acids is plotted against the respective GC measurements. For the prediction the spectral regions from 700 cm-1 to 1800 cm-1 and from 2800 cm-1 to 3100 cm-1 of the FTIR spectra were used. On the x-axis the measured values and on the y-axis the predicted values are plotted. The calibrated results are shown in blue, while validation results are shown in red. (b) The corresponding regression coefficients are shown. In (c) the fatty acid region from 2800 cm-1 to 3100 cm-1 is enlarged for the regression coefficient shown in (b).