Multi-modular engineering of 1,3-propanediol biosynthesis system in Klebsiella pneumoniae from co-substrate.

1,3-Propanediol (1,3-PDO) is a monomer for the synthesis of various polyesters. It is widely used in industries including cosmetics, solvents, and lubricants. Here, the multi-modular engineering was used to improve the concentration and tolerance of 1,3-PDO in Klebsiella pneumoniae. Firstly, the concentration of 1,3-PDO was increased by 25 %, while the concentrations of by-products were reduced considerably through one-step evolution which focused on the glycerol pathway. In addition, the 1,3-PDO tolerance was improved to 150 g L-1. Secondly, co-substrate transport system was regulated, and the 1,3-PDO concentration, yield, and productivity of the mutant were improved to 76.4 g L-1, 0.53 mol mol-1, and 2.55 g L-1 h-1, respectively. Finally, NADH regeneration was introduced and the recombinant strain was successfully achieved with a high productivity of 2.69 g L-1 h-1. The concentration and yield of 1,3-PDO were also improved to 86 g L-1 and 0.59 mol mol-1. This strategy described here provides an approach of achieving a superior strain which is able to produce 1,3-PDO with high productivity and yield.