Green production finds unlikely ally in genetically modified E. coli
Scientists have created a mutant bug that excretes a key ingredient for many plastics, drugs and other products when fed simple glucose.The American team tinkered with the genetic make-up of E. coli bacteria to create massively increased amounts of almost-pure succinate, a chemical usually obtained from dwindling supplies of fossil fuels.
E. coli and several other bacteria produce succinate naturally, but only in small amounts and as one of many by-products, making its recovery difficult and uneconomic.
But biochemists George Bennett and Ka-Yiu San have created a new bug which creates the valuable material more efficiently by removing genes that hinder the process and adding two new ones to increase the yield.
The development will throw up an interesting dilemma for many environmentalists, traditionally wary of genetic modification but keen to find alternatives to using non-renewable and polluting fossil fuels.
Succinate is widely used for a whole range of products and finding an alternative source has been a priority for many industrial chemists.
The new bug, which is currently only know by its laboratory label SBS550MG, has been engineered to produce succinate in two different ways.
The first exists naturally in 'wild' strains of E. coli but has been modified with the removal of four genes which interfere with the bacteria's ability to transform glucose into succinate or limits the amount it produces.
The second pathway for the process comes from the genes of two alien organisms, lactococcus bacteria and sorghum, which have been added to the new strain of E. coli.
Each genetic pathway metabolizes glucose and produces succinate via dissimilar chemical reactions, meaning the two don't compete or interfere with one another.
"Our experiments in the laboratory have produced near-maximum yields, with almost all the glucose being converted into succinate," said Dr San.
"The implementation was actually easier than we expected because the cells did the balancing themselves."
The bug is now being used commercially, as a Kansas-based agri-tech firm AgRenew Inc tries to scale up the results of the lab and develop effective ways to feed large cultures of the bacteria.
By Sam Bond