Fig. 1

Timing of thi6 thiamin concentration-responsive growth. The thi6 Saccharomyces cerevisiae mutant strain depicts a thiamin concentration-responsive growth when grown on different concentrations of thiamin standards [28]. A Quantification of the growth of thi6 was monitored in real-time as a proxy for thiamin content (see methods) using a TECAN Infinite 200 pro plate reader. The graph depicts the thi6 growth progression by monitoring Optical Density (OD), for twelve different thiamin concentrations, at 30 min timepoint intervals, for a total period of 24 h (h). Each concentration of the thiamin standard was tested in two technical replicates (2 × 12; 24 well plate). The data represent the mean ± Standard Error of at least 7 repeats (7 different days of measurements). Gray rectangles indicate timepoints that were used to generate growth concentration–response curves of the thi6 strain in the microbiological assay. Concentration-dependent growth curves were assessed at 17 h (B), 20 h (C) and 24 h (D) of growth. The correlation (R²) between the concentration of thiamin standard added, and the OD for a given timepoint of measurement is indicated. Taking the example of the 17 h timepoint, the concentration of thiamin in the standard is estimated by the following formula: concentration (nM) = e^{(OD+0.2248)/0.0658}. Note that the concentrations depicted (ranging from 0–421 nM) arise from the thiamin standard dilution series (ranging from 0–3770 nM) as used in the assay protocol (see methods for the preparation of the thiamin standard series and assay). E Chemical structure of most common vitamin B₁ vitamers. F Concentration-dependent growth of thi6 strain using two distinct concentrations of the most common vitamin B₁ vitamers (mean ± Standard Error of 3 repeats (analysis days) each consisting of 2 technical repeats, are shown). OD values were derived from the TECAN Infinite 200 pro plate reader, in which the measurements represent the measured OD subtracted by the OD measured at timepoint 0. Moreover, as the reading does not include correction for path length, OD values should only be interpreted in a relative way. TMP thiamin monophosphate, TPP thiamin pyrophosphate