Fig. 2

Optimization of media conditions to enhance TAL production in synthetic media containing 98 g/L glucose and 52 g/L xylose, as well as YPD (20 g/L glucose) as a control. A range of carbon to nitrogen (C:N) ratios were explored using urea or ammonium sulfate (AS) as the nitrogen source, by varying the amount of nitrogen source added. A Titers of TAL obtained from culture supernatant after two, four, and eight days of fermentation. B Growth of cultures in A, as measured by optical densities. C Comparisons of variations in experimental setup from the 40:1 C:N ratio using AS as the nitrogen source, in which the noted modification in the x-axis was made for each condition. D Growth of cultures in C, as measured by optical densities. E Comparison of titers in YPD media, and YPD supplemented with 2.5% DMSO, after five days of fermentation. F Optical densities of cultures in E. All error bars represent standard deviations of biological triplicates. P-values were calculated using a two-tailed type II Student’s t-test