A comprehensive review on microbial production of 1,2-propanediol: micro-organisms, metabolic pathways, and metabolic engineering

Abstract

1,2-Propanediol is an important building block as a component used in the manufacture of unsaturated polyester resin, antifreeze, biofuel, nonionic detergent, etc. Commercial production of 1,2-propanediol through microbial biosynthesis is limited by low efficiency, and chemical production of 1,2-propanediol requires petrochemically derived routes involving wasteful power consumption and high pollution emissions. With the development of various strategies based on metabolic engineering, a series of obstacles are expected to be overcome. This review provides an extensive overview of the progress in the microbial production of 1,2-propanediol, particularly the different micro-organisms used for 1,2-propanediol biosynthesis and microbial production pathways. In addition, outstanding challenges associated with microbial biosynthesis and feasible metabolic engineering strategies, as well as perspectives on the future microbial production of 1,2-propanediol, are discussed.

Keywords: 1,2-Propanediol; Metabolic engineering; Metabolic pathway; Micro-organism.

Fig. 1

Metabolic pathways for the production of 1,2-PDO from l-fucose and l-rhamnose (Deoxyhexose pathway). The genes in Fig. 1 are all from E. coli. fucP: l-fucose permease; rhaT: l-rhamnose permease; fucI: l-fucose isomerase; rhaA: l-rhamnose isomerase; fucK: l-fuculokinase; rhaB: l-rhamnulokinase; fucA: l-fuculose-1-phosphate aldolase; rhaD: l-rhamnulose-1-phosphate aldolase; fucO: propanediol oxidoreductase

Fig. 2

Metabolic pathways for the production of 1,2-PDO from glucose (Methylglyoxal pathway). The genes in Fig. 2 are all from E. coli. ALDO: fructose–bisphosphate aldolase; tpi: triose-phosphate isomerase; mgsA: methylglyoxal synthase; gldA: glycerol dehydrogenase; yqhD: alcohol dehydrogenase; fucO: propanediol oxidoreductase; Glyoxalase system: glyoxalase I (lactoylglutathione lyase), glyoxalase II (hydroxyacylglutathione hydrolase)

Fig. 3

Metabolic pathways for the production of 1,2-PDO from lactate (Lactate pathway). Acetate and ethanol synthesis pathway are from the proposed pathway for anaerobic degradation of lactic acid by L. buchneri [24]. Pct: propionate CoA-transferase (M. elsdenii); pduP: propanal dehydrogenase (S. enterica); yahK: lactaldehyde reductase (E. coli)