Increasing Escherichia coli membrane robustness to long-chain fatty acids
Product generation through genetically modified microorganisms has enabled scientists to produce hydrocarbons, antibodies, and proteins of their choosing. However, the inhibitory nature of these products reduces production rates and final titer of products. Genetically modifying microorganisms to withstand these products so they can continue to produce product at higher concentrations is just one way to bring these bioproducts to a competitive economic scale. Here, we investigate the deletion of two proteins, protein X and protein Y, associated with fatty acids in Escherichia coli MG1655. These proteins allow for the buildup up fatty acids in the cell, which degrade the cell membrane and inhibit growth. The knockout of protein X did not yield an increase final free fatty acid titer. However, the knockout of protein Y significantly decreased the final titer achieved, the opposite trend as expected. The double knockout of protein X and protein Y resulted in the same decrease in fatty acid titer as the protein Y knockout, but the double knockout stain exhibited drastically different growth rates. The double knockout enabled growth rates to rise, and the final titer was reached over twice as fast as the other three strains. The deviation from expected results could help understanding additional functions of these proteins.