EngineeringEscherichia colifor Direct Production of 1,2-Propanediol and 1,3-Propanediol from Starch

Diols are versatile chemicals used for multiple manufacturing products. In some previous studies,Escherichia colihas been engineered to produce 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO) from glucose. However, there are no reports on the direct production of these diols from starch instead of glucose as a substrate. In this study, we directly produced 1,2-PDO and 1,3-PDO from starch usingE. coliengineered for expressing a heterologous alpha-amylase, along with the expression of 1,2-PDO and 1,3-PDO synthetic genes. For this, the recombinant plasmids, pVUB3-SBA harboringamyAgene for alpha-amylase production, pSR5 harboringpct,pduP, andyahKgenes for 1,2-PDO production, and pSR8 harboringgpd1-gpp2,dhaB123,gdrAB, anddhaTgenes for 1,3-PDO production, were constructed. Subsequently,E. coliBW25113 (Delta pflA) and BW25113 strains were transformed with pVUB3-SBA, pSR5, and/or pSR8. Using these transformants, direct production of 1,2-PDO and 1,3-PDO from starch was demonstrated under microaerobic condition. As a result, the maximum production titers of 1,2-PDO and 1,3-PDO from 1% glucose as a sole carbon source were 13 mg/L and 150 mg/L, respectively. The maximum production titers from 1% starch were similar levels (30 mg/L 1,2-PDO and 120 mg/L 1,3-PDO). These data indicate that starch can be an alternative carbon source for the production of 1,2-PDO and 1,3-PDO in engineeredE. coli. This technology could simplify the upstream process of diol bioproduction.