Evolution for exogenous octanoic acid tolerance improves carboxylic acid production and membrane integrity

摘要: Carboxylic acids are an attractive biorenewable chemical, but as with many biorenewables, their toxicity to microbial biocatalysts limits fermentative production. While it is generally accepted that membrane damage the main mechanism of fatty acid toxicity, previous metabolic engineering efforts increased integrity did not enable carboxylic Here we used evolutionary approach improve tolerance exogenous octanoic acid, goal learning design strategies from this evolved strain. This evolution Escherichia coli MG1655 derivative at neutral pH in minimal media produced a strain only also hexanoic decanoic n-butanol and isobutanol. 5-fold higher titer than its parent when expressing Anaerococcus tetradius thioesterase. has been previously suggested intracellular acidification may contribute saw no evidence resistance acidification. Characterization showed had significantly altered polarization (fluidity), (leakage) composition relative parent. The changes included significant increase average lipid length variety growth conditions, including 30°C, 42°C, challenge ethanol challenge. more dynamic composition, showing both larger number fold abundance lipids. These results highlight importance cell increasing production fuels chemicals.