Metabolic engineering for the production of multi-methyl branched esters in Escherichia coli

HUGO GRAMAJO

Surrey

Workshop; Workshop of Synthetic Biology for Biotechnology and Bioengineering; 2015

Metabolic engineering for the production of multi-methyl branched esters in Escherichia coli Hugo Gramajo, Instituto de Biología Molecular y Celular de Rosario. IBR-CONICET. Facultad de Ciencias Bioquímicas y Farmacéuticas. UNR. Rosario, Argentina.Since the escalating cost of crude oil and the increasing concerns about its finite supply, there is an emerging strategic need to develop additional renewable products from plant, algae or microorganisms. In this context, there are considerable environmental and economic drivers to develop new and improved bio-based chemicals. Particularly for the lubricant industry, vegetable oils are considered a good source of natural lubricants; however their main disadvantages are their poor low temperature fluidity behavior and sensitivity to oxidation at high temperatures. The reason for the poor temperature properties is found in the molecular structure: i.e., the presence of double bonds in the alkyl side chains and the central β?CH group on the glycerol moiety of the triacylglycerol molecule. The β?hydrogen atom is easily eliminated through oxidation, which also leads to a weakening of the otherwise very stable ester linkage, and to further degradation of the oil. On the other hand, double bonds on the carbon chain are especially reactive and react with molecular oxygen to form radicals that lead to polymerization and degradation. Polymerization increases the viscosity of the oil, which further reduces its lubrication properties. In this sense, the inclusion of branched fatty acids in the base oil itself would therefore improve the properties of the oils. For example, the irregularity imparted by branched-chain fatty acids would disrupt the lipid packing ability of the hydrocarbon chains, thereby reducing the melting temperature of the oil.Some bacteria, especially those belonging to the actinomycetes group, produce very complex lipids. By using the metabolic pathways involved in the biosynthesis of these lipids and taking advantage of the exquisite metabolic flexibility of Escherichia coli we have designed and reconstructed a heterologous system capable of producing novel lipids compounds with improved lubricant properties. This new organism could serve as a novel platform for the production of bio-lubricants.