P38: Overexpression of marA enhancing resistance of E. coli against isoprenoids

Due to exhausting fuel reservoirs, high oil prices and politico-strategic problems it is pressing to produce biofuels as transportation energy alternative. Fossil fuel is a complex mixture of hydrocarbons including linear, branched, and cyclic alkanes, and aromatics. Isoprenoid based biofuel is promising alternative to replace the present hydrocarbon fuels. The Isoprenoid biosynthesis pathways could produce branched-chain and cyclic alkanes, alkenes, and alcohols with desired chain lengths. But their mass production is hampered due to their toxicity to host strain, E. coli. With respect to this it’s difficult to produce biofuel at the titers required for economic efficiency. So it is of utmost importance to develop tolerant host strain to pernicious isoprenoid biofuels. In our study we have over expressed different stress responsive genes (marA, cls, imp, and cti) which are suppose to provide tolerance against different hostile solvents. Plate overlay, broth overlay, viable cell count and gas chromatography analysis were carried out to observe any improved tolerance by the tested genes. In present work hexane is used as dilution solvent of isoprenoids. Overexpression of marA increased tolerance of E. coli to geraniol, farnesol, and myrcene but showed no effect on isopentenol, while cls, imp and cti overexpression failed to show any improved results. Mutant strain with marA deletion was much more sensitive to the isoprenoids, compared to its wild type strain. This work was supported by the 21C Frontier Microbial Genomics and Applications Center Program, EB-NCRC (Grant No. R15-2003-012-02001-0), and BK21 program of Korea.