Dynamic Tuning of Glycolytic Flux for Heterologous Production with a ‘Glucose Valve'

With the rising costs of petrochemical feedstocks and growing concern regarding the sustainability of chemical synthesis, microbial production has become an increasingly attractive alternative to the production of commodity and specialty chemicals.  Great strides have been made with the development of existing and novel chemistries to generate a wide array of compounds; however, efforts to make these systems economically viable still face a number of challenges.  Notable among these is the issue of pathway flux manipulation.  In this study, we examine this problem as it pertains to the redirection of glucose from glycolysis.  

We have been able to create a new E. coli platform that decouples glucose transport and phosphorylation allowing us to independently control the flux of glucose and enable the construction of pathways requiring unphosphorylated glucose directly.  Through the use of transcriptional and post transcriptional devices such as antisense RNA, inverting gene circuits and constitutive promoters, we explore a wide range of glycolytic flux and study its impact on both heterologous pathway productivity and cellular processes.  In this manner, we are able to increase molar yield in a model glucose consuming pathway by at least 50%.  These devices also allow for novel dynamic optimization schemes, pathway development and perhaps improvement of existing processes.  In this talk, I will highlight some of the successes and challenges associated with flux manipulation as well as future areas of development.