Glycerol conversion to 1, 3-Propanediol is enhanced by the expression of a heterologous alcohol dehydrogenase gene in Lactobacillus reuteri

Abstract

In this work, Lactobacillus reuteri has been metabolically engineered for improving 1, 3-propanediol (1, 3-PD) production by the expression of an Escherichia coli alcohol dehydrogenase, yqhD, that is known to efficiently convert the precursor 3-hydroxypropionaldehyde (3-HPA) to 1, 3-PD. The engineered strain exhibited significantly altered formation rates for the product and other metabolites during the fermentation. An increase in the 1, 3-PD specific productivity of 34% and molar yield by 13% was achieved in the clone, relative to the native strain. A concomitant decrease in the levels of toxic intermediate, 3-HPA, was observed, with the specific productivity levels being 25% lesser than that of the native strain. Interestingly, the recombinant strain exhibited elevated rates of lactate and ethanol formation as well as reduced rate of acetate production, compared to the native strain. The preferential utilization of NADPH by YqhD with a possible decrease in the native 1, 3-PD oxidoreductase (NADH-dependent) activity, could have resulted in the diversion of surplus NADH towards increased lactate and ethanol productivities.

Genetic engineering ofLactobacillus diolivorans

“…Considering that the expression of PDO-DH (NADPH) showed an increased activity of 1,3-propanediol oxidoreductase for both NADH and NADPH, the unchanged metabolite concentrations except for increased 1,3-propanediol concentrations can be explained. This is in contrast to what has been reported by Vaidyanathan et al (2011) that L. reuteri expressing NADPH-dependent alcohol dehydrogenase YqhD from E. coli showed increased lactic acid and ethanol production. It has been suggested that the overexpression of YqhD led to a preference for utilization of NADPH over NADH for the reduction of 3-HPA to 1,3-propanediol due to a lower activity of the native NADH-dependent 1,3-propanediol oxidoreductase.…”

“…This is in contrast to what has been reported by Vaidyanathan et al . () that L. reuteri expressing NADPH‐dependent alcohol dehydrogenase YqhD from E. coli showed increased lactic acid and ethanol production. It has been suggested that the overexpression of YqhD led to a preference for utilization of NADPH over NADH for the reduction of 3‐HPA to 1,3‐propanediol due to a lower activity of the native NADH‐dependent 1,3‐propanediol oxidoreductase.…”

Toward glycerol biorefinery: metabolic engineering for the production of biofuels and chemicals from glycerol

“…Of particular interest is its use as a monomer for the synthesis of polyethers, polyurethanes and polyesters such as polytrimethylene terephthalate (PTT). Several species of microorganisms, including Klebsiella ( K. pneumoniae and K. oxytoca ), Clostridia ( C. butyricum and C. pasteurianum ), Enterobacter ( E. agglomerans ), Citrobacter ( C. freundii ) and Lactobacilli ( L. brevis and L. buchneri ), possess the ability to convert glycerol into 1,3-PDO [ 22 – 25 ]. Among the natural producers, K. pneumoniae and C. butyricum are the most promising species due to their high tolerance to glycerol inhibition and high production of 1,3-PDO.…”

The ability of Clostridium bifermentans strains to lactic acid biosynthesis in various environmental conditions

“…Accordingly, it is necessary to find a new effective method to utilized this amount of crude glycerol. The research on production 1,3-PD from crude glycerol by microbiological way is extensively described worldwide e.g., (Hiremath et al 2011; Mendes et al 2011; Vaidyanathan et al 2011; Chatzifragkou et al 2011; Wilkens et al 2012; Ringel et al 2012), but only a few papers concern the production of lactic acid from this by-product, and moreover, publications concentrate mainly on genetic engineered strains (Posada et al 2012; Ruhal & Choudhury 2012); at the same time only a few papers discuss lactic acid production from other renewable resources (Hofvendahl & Hahn-Hägerdal 2000; Yadav et al 2011). During our work it occurred that Cl.…”