2.1 Strains and media
All strains and plasmids used in this study were listed in supplementary
tables S1 and S2, respectively. S. cerevisiae were cultivated in
YPD medium containing 10 g/L yeast extract, 20 g/L peptone and 20 g/L
glucose. Escherichia coli DH5α was grown in LB medium (5 g/L
yeast extract, 10 g/L NaCl and 10 g/L tryptone), and 100 mg/mL
ampicillin was added. Synthetic Dropout (SD) medium was composed of 20
g/L glucose and 6.7 g/L amino acid-free yeast nitrogen source (YNB).
Minimal (Delft) medium was adopted to cultivate S. cerevisiaestrains [20] containing 20 g/L glucose, 2.5 g/L
(NH4)2SO4, 14.4 g/L
KH2PO4, 0.5 g/L
MgSO4•7H2O, 2 ml/L trace metals, 1 ml/L
vitamin solution, and amino acids were supplemented if necessary. Solid
plates contain 20 g/L agar.
The specific amounts of exogenous amino acids or nucleotides added in
media are as follows. In preliminary experiments, low (20-60 mg/L,
Figure S2) and high (100 mg/L, Figure S3) concentrations of amino acids
or nucleotides were added in the culture medium, respectively, to
determine the growth and production of the auxotrophic strains.
Furthermore, we set 100 mg/L as the baseline to test the essential
amounts of amino acids and nucleotides for each auxotroph to restore
cell growth and bio-productions. For example, the concentrations of
leucine, tryptophan, lysine (Figure 2) and methionine (Figure 3) were
increased from 100 mg/L to 500 and 1,000 mg/L, respectively. The
concentrations of histidine, arginine (Figure 4), uracil and adenine
(Figure 5) were decreased from 100 mg/L to 20 and 60 mg/L.