(520d) Anaerobic Fermentation Of Glycerol In Escherichia Coli: A New Path To Biofuels And Biochemicals

The fermentative metabolism of glycerol in the Enterobacteriaceae has long been considered a property of species that synthesize 1,3-propanediol (1,3-PDO). However, we have discovered that E. coli, an organism lacking the 1,3-PDO pathway, can fermentatively metabolize glycerol. We have collected genetic and physiological evidence supporting: (i) the fermentative nature of this process, (ii) the role of fermentative pathways, and (iii) the incorporation of glycerol into cell mass. A novel trunk pathway responsible for glycerol conversion into glycolytic intermediates was identified. We propose a new paradigm for the 1,3-PDO-independent fermentation of glycerol in enteric bacteria in which trunk and auxiliary pathways work in partnership to attain redox balance. Finally, we have illustrated the significance of our findings for the development of microbial platforms that will convert low-priced glycerol (an inevitable byproduct of biodiesel fuel production) to higher value fuels and chemicals. Our current efforts focus on the identification of genetic and environmental determinants of glycerol fermentation by using system-level techniques, including global gene and protein expression analysis in combination with in silico and in vivo flux analysis. We will discuss at the meeting the implications of our findings for: (1) the elucidation of glycerol fermentation in enteric bacteria and (2) the metabolic engineering E. coli to convert glycerol into reduced chemicals.