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Figure 1. Sequential production of paraxanthine and
7-methylxanthine from caffeine by E. coli strain MBM019. Price per gram
of each compound is based on the lowest retail values found from Sigma
Aldrich (March 2022).
Figure 2. N -demethylation of caffeine (red; ▲) to
paraxanthine (light grey; ♦) and 7-methylxanthine (dark grey; ■) byE. coli strain MBM019. The supernatant from Round 1 was mixed
with fresh MBM019 cells to continue the conversion of caffeine. This
process was repeated until nearly complete conversion of caffeine to
paraxanthine and 7-methylxanthine was achieved at the end of Round 4.
Mean concentrations and standard deviations of triplicate results are
shown.
Figure 3. Direct comparison of conversion of caffeine (red) to
paraxanthine (light grey) and paraxanthine to 7-methylxanthine (dark
grey) by the genetically engineered E. coli strain MBM019.
Hatching indicates the concentration of substrate consumed. Solid
coloring indicates the concentration of product generated. Substrates
for each reaction are also listed at the bottom of the graph. Reactions
were conducted at a 2 mL volume in 50 mM KPi with cells
at an OD600 of 5 and substrate concentrations of 1 mM.
Reaction conditions were set to 37℃, 200 rpm for 5 hours. Mean
concentrations and standard deviations of triplicate results are shown
from the conclusion of a five-hour resting cell assay.