Recent advances in metabolic engineering of microorganisms for the production of monomeric C3 and C4 chemical compounds.

Bio-based C3 and C4 bi-functional chemicals are useful monomers in biopolymer production. This review describes recent progresses in the biosynthesis of four such monomers as a hydroxy-carboxylic acid (3-hydroxypropionic acid), a dicarboxylic acid (succinic acid), and two diols (1,3-propanediol and 1,4-butanediol). The use of cheap carbon sources and the development of strains and processes for better product titer, rate and yield are presented. Challenges and future perspectives for (more) economical commercial production of these chemicals are also briefly discussed.