Background 1,3-Propanediol is the starting point of a new-generation polymer with superior properties which can be used in many industrial fields. 3-Hydroxypropionaldehyde and lactate have been identified as two important metabolites in the biological route of 1,3-propanediol bioconversion from glycerol. Here, influence of lactate on the inhibition caused by 3-hydroxypropionaldehyde of 1,3-propanediol fermentation by Klebsiella pneumoniae is reported.
Methods The influences of 3-hydroxypropionaldehyde and lactate on 1,3-propanediol production were investigated in normal and lactate pathway deficient strains with different fermentation conditions.
Results By using the strains KG1 and L-type lactate dehydrogenase-deficient mutant (KG1Δldh), the results indicated that an early accumulation of 3-hydroxypropionaldehyde directly inhibited the 1,3-propanediol production rather than through lactate accumulation during the late stage of fermentation. Then, the influence of extra addition of lactate on the late stage of fermentation was investigated, and the inhibitory effect of lactate did not appear. At last, it was found that by reducing 3-hydroxypropionaldehyde accumulation in the early stage of fermentation, the concentration and yield of 1,3-propanediol increased by 18% and 16%, respectively, over the initial experimental levels.
Conclusions An early accumulation of 3-hydroxypropionaldehyde directly decreased the final 1,3-propanediol concentration rather than through lactate accumulation during the late stage of fermentation.
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