Bacteria success for succinate process

A key ingredient of many plastics, drugs, solvents and food additives, succinate has become the focus of many research teams trying to create succinate-producing bacteria that can be used on sustainable feedstocks such as argicultural crops.

‘Succinate can be used to make everything from non-corrosive airport deicers to non-toxic solvents,’ says George Bennett, professor and chair of the department of biochemistry and cell biology at Rice University, Houston, Texas.

‘It is a high-priority chemical that the US Department of Energy has targeted for biosynthesis. Some bacteria make it naturally, so we have a metabolic starting place for large-scale fermentation.’

The centrepiece of Rice’s succinate technology is a mutant form of the E coli bacteria that makes succinate as its only metabolic by-product. Bennett and co-developer Ka-Yiu San are working with Kansas-based AgRenew, which has just begun trials on how to use farm-grown products like grain sorghum (millet) as feedstocks for the succinate-producing bacteria.

Bennett and San’s genetically modified E coli - known only as SBS550MG – produces succinate in two different ways. Each genetic pathway metabolises glucose and produces succinate via dissimilar chemical reactions. The researchers designed the paths to be complementary, but even so they were pleased to see how well the process worked once both paths were put in place.

‘Our lab experiments have produced near-maximum yields, with almost all the glucose being converted into succinate,’ says San. ‘The implementation was actually easier than we expected because the cells did the balancing themselves.