The Bifi-RuMP Pathway: a Synthetic High Yield Methanol Assimilation Pathway

With the current and expected continued low cost, domestic supply of natural gas one carbon feedstocks, including methane and methanol, are an attractive input into industrial bioprocesses. We present our initial work focused on the evaluation and construction of an engineered catabolic pathway for high yield methanol assimilation. The designer Bifi-RuMP pathway combines the key enzyme of the Bifidobacterium shunt, phosphoketolase, into the Ribulose-monophosphate pathway (RuMP). Theoretically, this designer pathway allows for the combination of two moles of methanol (C1) into one mole of acetyl-CoA (C2), enabling a maximal carbon efficiency of 100% compared to the natural RuMP pathway which produces 1 mole of acetyl-CoA (C2) from three moles of methanol (C1) at a carbon efficiency of 66.7%. The potential impact of this pathway is up to a 50% increase in yield of products made from methanol. Whole cell metabolic models and initial experimental results support the feasibility of implementing the Bifi-RuMP pathway in E. coli and other host microbes. These initial results also highlight challenges to the functional implementation of this and other synthetic catabolic pathways, including cycles, into heterologous hosts.