Strategies to Enhance the Biosynthesis of Monounsaturated Fatty Acids in Escherichia coli

다국어 초록 (Multilingual Abstract)

Fueled by a variety of industrial applications ranging from bioplastics to cosmetics and pharmaceuticals, the global demand for unsaturated fatty acids is steadily rising. Most of these applications build on monounsaturated fatty acids with a chain length of 16 or 18 carbon atoms, rendering these compounds valuable industrial assets. While of high industrial interest, monounsaturated fatty acids with a chain length of 8 to 12 carbon atoms are hard to produce using conventional chemical or plant-based production ways. As a consequence, these compounds are expensive and not readily available for large-scale industrial applications. Recent advances in metabolic engineering have put forward microbes as cost-efficient factories to produce numerous chemical compounds. In this respect, the model organism Escherichia coli is considered an interesting species as it can grow on various feedstocks and a plethora of genetic information is available, facilitating expression of exogenous enzymes. For the purpose of shifting the fatty acid pool towards monounsaturated fatty acid, thioesterases and desaturases represent suitable candidate enzymes. The former stop chain elongation, reacting on acyl-chains of specific chain length and saturation level, whereas the latter directly target fatty acids to convert them into unsaturated analogues. In this review we summarize thioesterases and desaturases that have been introduced in E. coli to enrich unsaturated fatty acids. Furthermore, we discuss advantages of using bacteria for the production of designer compounds including but not limited to medium-chain monounsaturated fatty acids.