Escherichia coli Engineered to Produce Renewable Propane

A team of scientists from Finland and the United Kingdom has engineered the common gut bacteria, Escherichia coli , to generate renewable propane.

Escherichia coli Engineered to Produce Renewable Propane

This false-color scanning electron micrograph shows Escherichia coli . Image credit: Rocky Mountain Laboratories / NIAID / NIH.
Propane is a naturally occurring gas composed of three carbon atoms and eight hydrogen atoms. It is produced as a by-product of two processes – natural gas processing and petroleum refining – but both are finite resources.
In its current form it makes up the bulk of liquid petroleum gas, which is used in many applications, from central heating to camping stoves and conventional motor vehicles.
In a research paper released by the journal Nature Communications , Dr Patrik Jones of Imperial College London and the University of Turku in Finland and his colleagues have reported, for the first time, a synthetic metabolic pathway for producing renewable propane.
They used Escherichia coli to interrupt the biological process that turns fatty acids into cell membranes and instead channel it toward the production of propane.
This was achieved by engineering a pathway that consisted of three key enzymes: i) a thioesterase to produce butyric acid; ii) a carboxylic acid reductase to convert butyric acid into butyraldehyde; and iii) an aldehyde-deformylating oxygenase (ADO) to form propane.
Previous attempts to use the ADO enzyme have proved elusive as scientists have been unable to harness the natural power of the enzyme to create cleaner fuel.
But Dr Jones’ team discovered that by stimulating ADO with electrons, it is possible to substantially enhance the catalytic capability of the enzyme and ultimately produce greater levels of propane.
The level of propane that the scientists produced is currently 1,000 times less than what would be needed to turn it into a commercial product, so they are now working on refining their synthetic process.
They said that their main goal is to insert this engineered system into photosynthetic bacteria, so as to one day directly convert solar energy into chemical fuel.