The randomly generated mutants were then

screened for ethanol production. Strains were cultured in media containing

glucose, xylose and arabinose to reflect the composition of agricultural

biomass. The bacterial strains were cultured for a period of fifteen hours and

samples of media were collected at regular timepoints (0, 3, 6, 9, 12 and 15

hours) to track the production of ethanol.

A graph of ethanol production in the PET #A

strain and 2 mutant strains; PET #X, and PET #Y are shown below.

Which strain produced the most ethanol at 15

hours?