Membrane engineering via trans-unsaturated fatty acids production improves succinic acid production in Mannheimia succiniciproducens.

Engineering of microorganisms to produce desired bio-products with high titer, yield, and productivity is often limited by product toxicity. This is also true for succinic acid (SA), a four carbon dicarboxylic acid of industrial importance. Acid products often cause product toxicity to cells through several different factors, membrane damage being one of the primary factors. In this study, cis-trans isomerase from Pseudomonas aeruginosa was expressed in Mannheimia succiniciproducens to produce trans-unsaturated fatty acid (TUFA) and to reinforce the cell membrane of M. succiniciproducens. The engineered strain showed significant decrease in membrane fluidity as production of TUFA enabled tight packing of fatty acids, which made cells to possess more rigid cell membrane. As a result, the membrane-engineered M. succiniciproducens strain showed higher tolerance toward SA and increased production of SA compared with the control strain without membrane engineering. The membrane engineering approach employed in this study will be useful for increasing tolerance to, and consequently enhancing production of acid products.