Effect of culture conditions on 3-hydroxypropionaldehyde detoxification in 1,3-propanediol fermentation by Klebsiella pneumoniae

Abstract

1,3-Propanediol (1,3-PD) production is favored by high amount of glycerol which also contributes to the lethal 3-hydroxypropionaldehyde (3-HPA) accumulation. The influences of three culture conditions including initial glycerol concentration, stirring rate, and oxidoreduction potential (ORP) regulation on 3-HPA accumulation and 1,3-PD production were investigated. 3-HPA detoxification was available at initial glycerol concentration, aeration rate and stirring rate of up to 40 g l −1, 0.5 vvm air flow and 250 rpm, respectively. Alternatively, the stirring rate of 300 rpm was sufficient to fulfill the fermentation with initial 50 g glycerol l −1. In addition, 3-HPA accumulation could be avoided at the initial 50 g glycerol l −1 under the regulated reducing conditions (−200 and −400 mV). However, ORP regulation was not convenient and feasible for the industrial production in that more carbon was distributed to weak organic acids. Consequently, two-stage fed-batch strategy was presented to achieve 3-HPA detoxification and maintain the expected high productivity of 1,3-PD, in which the batch culture stage was conducted at initial glycerol concentration and stirring rate of 40 g l −1 and 250 rpm, respectively, and the feeding culture stage was performed at stirring rate of 300 rpm. 74.07 g 1,3-PD l −1 was produced in 24 h with the yield and productivity of 0.62 mol mol −1 and 3.08 g l −1 h −1.