Overproduction of free fatty acids in E. coli: Implications for biodiesel production

Modular optimization of multi-gene pathways for fatty acids production in E. coli

“…1b). Indeed, improved cellular concentration of malonyl-CoA by expression of E. coli or heterologous ACC has proven to be an effective approach to increase the production titre of a range of malonyl-CoA-derived compounds including flavonoids 20 , polyketides 21 and fatty acids 4,22 .…”

“…Early metabolic engineering studies on fatty acid production have been dedicated to optimizing precursor supply and the specificity of plant fatty acyl-ACP thioesterase 4,6,10,30,31 . Engineering the reversal of b-oxidation pathway 7 and a dynamic sensor-regulator system 32 have also led to the production of fatty-acid-derived long chain chemicals and fuels.…”

“…The bioreactor was controlled at batch mode in the first 8 h and then switched to fed-batch mode by feeding 5 N ammonium hydroxide and 40% glucose (w/w). pH was maintained at 6.8 by feeding NH 4 OH and glucose was fed at a constant flow rate of 1.235 ml min À 1 with two independently controlled peristaltic pumps. Induction of protein expression was performed by adding 2.4 g IPTG and switching the cultivation temperature to 34 1C at 8 h of fermentation (OD ¼ 13).…”

“…With physicochemical properties closely resembling those of petroleum-based fuels, fatty acid-based fuels offer some unique advantages as compared with other fuel supplements (ethanol or butanol) such as lower hygroscopicity, miscibility with diesel fuels, lower downstream purification costs and compatibility with existing infrastructure 3 . Therefore, a number of fatty-acid-derived fuel molecules including free fatty acids 4 , alkane/alkene hydrocarbons 5,6 , fatty alcohols 7 , alkyl ketones 8 and triacylglyceride 9 have been produced from the fatty acid biosynthetic pathway. For instance, manipulation of precursor malonyl-CoA availability along with the expression of specific plant acyl-ACP thioesterases have resulted in fatty acid production at 2.5 g l À 1 in E. coli 4,10 .…”

“…Therefore, a number of fatty-acid-derived fuel molecules including free fatty acids 4 , alkane/alkene hydrocarbons 5,6 , fatty alcohols 7 , alkyl ketones 8 and triacylglyceride 9 have been produced from the fatty acid biosynthetic pathway. For instance, manipulation of precursor malonyl-CoA availability along with the expression of specific plant acyl-ACP thioesterases have resulted in fatty acid production at 2.5 g l À 1 in E. coli 4,10 . A consolidated bioprocess combined fatty acid pathway with xylan-utilization pathway led to fatty acid ethyl esters production at 11.8 mg l À 1 (ref.…”