Enhanced Utilization of Non-Favored Sugars from Marine Biomass By Re-Designed Escherichia coli

Marine biomass, known as the third generation of biomass for replacing fossil fuels, has many advantages rather than conventional biomass due to its high biomass productivity, carbon fixation rate and easy pretreatment process, etc. Macroalgae, which is main part of marine biomass, contains various kinds of sugars such as glucose, galactose, and alginate. However, the challenging problem for using macroalgae as a substrate is that these sugars are not usually favored and utilized by many microorganisms such as Escherichia coli. Slow utilization rate of non-favored sugar limits reduced carbon flux and results in low productivity and titer and production using non-utilizable sugar is virtually impossible.  In this research, we tried to develop E.coli to utilize galactose and alginate from marine biomass and to produce some commodity chemicals. For utilization of these sugars, rationally designed pathway with synthetic promoter, 5’UTR, terminator for maximum catalytic activity were introduced. And downstream pathway for production were fine-tuned at a key node. With this approach, the engineered strain shows enhanced utilization of both galactose and alginate and production of biochemicals. Finally, we could confirm the possibility of marine biomass as carbon source to produce many valuable bioproducts instead of fossil fuel.