Enhanced 1,3-propanediol production with high yield from glycerol through a novel Klebsiella-Shewanella co-culture.

BACKGROUND

1,3-Propanediol (1,3-PDO) is a platform compound, which has been widely used in food, pharmaceutical and cosmetic industries. Compared with chemical methods, the biological synthesis of 1,3-PDO has shown promising applications owing to its mild conditions and environmental friendliness. However, the biological synthesis of 1,3-PDO still has the problem of low titer and yield due to the shortage of reducing powers.

RESULTS

In this study, Klebsiella sp. strain YT7 was successfully isolated, which can synthesize 11.30 g/L of 1,3-PDO from glycerol in flasks. The intracellular redox regulation strategy based on the addition of electron mediators can increase the 1,3-PDO titer to 28.01 g/L. Furthermore, a co-culturing system consisting of strain YT7 and Shewanella oneidensis MR-1 was established, which can eliminate the supplementation of exogenous electron mediators and reduce the by-products accumulation. The 1,3-PDO yield reached 0.44 g/g and the final titer reached 62.90 g/L. The increased titer and yield were attributed to the increased redox levels and the consumption of by-products.

CONCLUSIONS

A two-bacterium co-culture system with Klebsiella sp. strain YT7 and S. oneidensis strain MR-1 was established, which realized the substitution of exogenous electron mediators and the reduction of by-product accumulation. Results provided theoretical basis for the high titer of 1,3-PDO production with low by-product concentration.