Effect of SAM-Dependent Methyltransferases from <i>Halomonas</i> sp. YLGW01 on Phospholipid Fatty Acids Composition and Production of Polyhydroxalkanoates in <i>Escherichia coli</i>

The bacterial membrane changes in response to growth conditions such as salt concentration, temperature, and growth inhibitors. As membrane fatty acid related genes are important in controlling the membrane composition, we studied two genes <i>i.e.</i> cyclopropane fatty acid synthase (<i>cfa</i>) and cis-vaccinate 11-methyltransferase (<i>ufaM</i>) that designated to S-adenosylmethionine (SAM)-dependent methyltransferase derivatives from <i>Halomonas</i> sp. YLGW01. These two genes are related to a response to external growth conditions by controlling the fluidity of membrane changes. The role of these two genes (<i>cfa</i> and <i>ufaM</i>) was accessed by overexpression in <i>Escherichia coli</i> and results showed an evident increase in the levels of cyclic fatty acid and detection of furan fatty acid intermediate analyzed by Gas chromatography Mass spectrometer (GC-MS), respectively, resulting in changes of phospholipid fatty acids (PLFA) and membrane properties. Overexpression of these genes in engineered polyhydroxyalkanoate (PHA) producing <i>E. coli</i> strain promoted the bacterial growth (1.6-fold) and PHA accumulation (2-fold). Overall, this study showed two membrane fatty acid synthases, <i>ufaM</i> and <i>cfa</i> able to change membrane fatty acid composition and have the potential to improve cell's robustness and PHA production capability.