BACKGROUND: Bioconversion of methanol derived from CO RESULTS: A combinatorial metabolic engineering strategy targeting precursors supply and 3-HP export was applied to the original 3-HP producing K. phaffii strain harboring the synthetic β-alanine pathway and a mutated NADP-dependent formate dehydrogenase from Pseudomonas sp. 101 (PseFDH(V9)). To do so, several genes encoding enzymes catalyzing reactions immediately upstream of the β-alanine pathway were overexpressed to enhance precursors availability. However, only the overexpression of the pyruvate carboxylase PYC2 gene significantly increased the 3-HP yield on biomass (Y CONCLUSIONS: Our results point out the potential of lactate transporters to efficiently drive 3-HP export in K. phaffii, leading to higher titers, yields, and productivities, even at lower pH conditions.