Commercially viable approach to turn sugar into 1,4-butanediol from of E. coli bacteria

A commercially viable approach for turning sugar into 1,4-butanediol (BDO) using a metabolically engineered strain of E. coli has been developed by US sustainable chemicals company Genomatica. This could offer a cost effective and green alternative for producing BDO and other major chemicals using a wide range of renewable feedstocks. BDO is a well established commodity chemical. Around 1.4 mln tons are produced each year, with a market value of US$4 bln (£2.5 bln). It is used to manufacture a huge range of industrial and consumer products, including solvents, plastics and spandex. 'Genomatica's bio-BDO is the first ever to be produced directly from renewable feedstocks - like dextrose and sucrose - without additional chemical processing steps, and at lower cost than current oil or natural gas-based BDO,' says co-author and director of technology development at Genomatica, Stephen Van Dien. 'We estimate that the entire worldwide production of BDO could be done using less than 2% of the world's sugar.' The team used an algorithm to predict biochemical pathways that could turn convert E.coli metabolites into BDO. They then identified enzymes in other organisms that could catalyse these steps and selected the best ones to assemble a non-natural pathway. This pathway was then expressed in E. colithat was engineered to direct carbon and energy resources to BDO production. 'This optimised strain for BDO production will certainly be a platform host that can lead to a commercial process,' says Hal Alper at the University of Texas at Austin, US. 'The algorithm developed here for pathway and strain construction will certainly advance and influence future de novo metabolic engineering efforts and lay the groundwork for future advances in the field of industrial biotechnology.' The engineered microbe is able to produce BDO at concentrations of 18g per litre. Although this is not high enough for commercialisation, it is a significant feat because these concentrations would ordinarily kill the cell. However, Van Dien tells Chemistry World that Genomatica has been designing organisms that can tolerate commercial-scale BDO production. 'We have already reached 100g of bio-BDO per litre.' Genomatica expects to open their first commercial plant by the end of 2013, producing around 450,000g of product per year. The fermentation and separation processes to obtain bio-BDO are simpler, cheaper, use less energy and operate at lower temperatures and pressures than conventional petrochemical methods. 'As a result, our process plants can economically be "right-sized" to the needs of a customer or region, and be located closer to feedstock and/or customers,' Van Dien says.