Researchers in the UK have taught E. coli to produce hepta-1,3,5-triene, a compound used in the chemical industry. The authors, published in ACS Synthetic Biology, hope that their proposed metabolic pathway will be an environmentally friendly alternative to obtaining this substance from fossil fuels.
Polyunsaturated alkenes are used in the production of pharmaceuticals and the synthesis of polymers, and now these substances are obtained from fossil fuels. Instead, scientists are looking for a renewable alternative.
One of the available options is to apply metabolic engineering techniques. Researchers have already learned to force bacteria to produce certain substances necessary for humans (including those that are not characteristic of these bacteria), or, conversely, to break down unnecessary ones (for example, polyethylene). To do this, scientists can overexpress the necessary genes in bacteria, block competing metabolic pathways, or express genes specific to other microorganisms, as well as apply enzyme engineering techniques. Work is underway to expand the list of substances that can be obtained using metabolic engineering methods.
There are decarboxylase enzymes capable of converting unsaturated carboxylic acids into the corresponding alkenes. It has also been shown that the bacterium Pantoea agglomerans in the natural process of biosynthesis of andrimidide, important for its metabolism, produces as an intermediate a derivative of 2,4,6-octatrienic acid. Combining these facts, scientists from the University of Manchester, David Leys, came up with a way to teach E. coli to synthesize hepta-1,3,5-triene, one of the representatives of polyunsaturated alkenes.
To begin with, biologists removed seven genes (which accounted for a third of the cluster) from the cluster of P. agglomerans genes required for andrimid synthesis, and introduced the remaining construct into Escherichia coli cells. Thus, 2,4,6-octatrienic acid with a concentration of 14.7 ± 2.0 milligrams per liter was developed. Interestingly, the authors tried to increase the yield of the product by transforming the genetic construct, but as a result got the opposite result – the complete absence of matter. The researchers suggested that there are some elements, not yet known to them, that control acid synthesis, and this will be known in future experiments.
Next, the scientists combined the resulting working construct with the decarboxylase gene from fungal cells. The production of hepta-1,3,5-triene was confirmed by gas chromatography coupled by mass spectrometry. The researchers estimated that the product concentration was 3.4 ± 0.3 milligrams per liter. The authors believe that they have shown an important example of the production of unsaturated hydrocarbons in vivo.
Not only biologists and chemists, but also physicists like to experiment with E. coli. For example, Spanish scientists tore a E. coli cell.