Working with Goodyear, biotechnology company Genencor has been engineering bacteria that make isoprene--the chemical used to make tire rubber--from sugars derived from biomass. But ramping up microbial production of isoprene to such a scale that it can compete with petroleum-derived rubber has proven to be a major challenge.
Yesterday at the American Chemical Society meeting in San Francisco, researchers from a Palo Alto, CA-based research division of Genencor described further modifications to the metabolic pathways of the microbes that improve the yield of bioisoprene. The company will decide on plans for building a bioisoprene pilot plant next year.
Microbes including E. coli naturally make small amounts of isoprene as part of their metabolism, but not nearly enough to be used on an industrial scale. To improve the yield, bioengineers at Genencor, which began working on bacterial systems for producing isoprene in 2007, initially made changes to two metabolic pathways that converge to create an isoprene precursor. But yields were still low because the bacteria's existing genetic machinery takes a meandering path to create isoprene from this precursor. In the most recent results, the company added to the E. coli a plant gene coding for isoprene synthase, an enzyme that converts the precursor directly into isoprene.