Pathway Engineering via Synthetic Biology

Microbial synthesis of value-added products such as chemicals, natural products, and fuels typically depends upon the creation or introduction of heterologous metabolic pathways into the production hosts.  Balancing the flux of a heterologous metabolic pathway is difficult yet critical to the success of metabolic engineering. Here we report the development of a series of synthetic biology approaches for pathway engineering and optimization.  Our first approach is to explore various combinations of the enzyme homologues with different properties. Our second approach, so-called Customized Optimization of Metabolic Pathways by Combinatorial Transcriptional Engineering (COMPACTER), is to explore various combinations of the promoters with varying strengths for each pathway gene. Our third approach, so-called induced pathway optimization by antibiotic doses (iPAD), is to enable modular optimization of multi-gene pathways by different combinations of antibiotic concentrations. These approaches have been successfully used to engineer a variety of important pathways including the cellobiose utilization pathway, the xylose utilizing pathway, the lycopene biosynthetic pathway and the n-butanol biosynthetic pathway.