Overview of the adaptive laboratory evolution experiment. Overview of the adaptive laboratory evolution experiment. (A) Schematic drawing of the xylose to D-lactate pathway. PPP, the pentose phosphate pathway; Xylulose-5-P, xylulose-5-phosphate. (B) Serial transfers of E. coli strain XW043 were cultured independently three times, resulting in three evolved populations, from which CM2, LP2, and TL1 were isolated. Extracellular xylose and D-lactate were determined for each transfer after 48 h of fermentation. (C) Primary convergent mutations were characterized using genome sequencing and allelic replacements. Christian Sievert et al. PNAS 2017;114:28:7349-7354 ©2017 by National Academy of Sciences