Patent ID: 8329444

Claim:
A process for making a Zymomonas mobilis strain more tolerant to an inhibitor comprising: a) growing a Zymomonas mobilis strain in a medium substantially free of an inhibitor; b) sequentially culturing the Zymomonas mobilis strain in the presence of consecutively higher concentrations of the inhibitor; and c) isolating a mutant strain having an adaptive mutation to a higher inhibitor concentration without NTG mutagenesis; wherein the inhibitor comprises acetic acid and wherein the isolated Zymomonas mobilis mutant strain is characterized by substantially exhibiting one or more of the following characteristics: (1) a lag phase of less than about one day; or (2) a specific growth rate of at least about 0.15 h −1 ; or (3) an ethanol yield of at least about 95% of the theoretical yield; wherein the one or more characteristics are exhibited while fermenting at a pH of about 6 in an RM medium with 50 g/L glucose and 1.6% acetic acid concentration.