Effects of gltA and arcA Mutations on Biomass and 1,3-Propanediol Production in Klebsiella pneumoniae

We have previously engineered a Klebsiella pneumoniae strain to increase the 1,3-production (1,3-PDO) yield from glycerol. Here, we describe the further engineering of this strain to improve the biomass formation, resulting in an increase in the 1,3-PDO production. The amino acid lysine at the 167th position in citrate synthase was substituted with alanine using genome editing method to reduce the binding affinity of the enzyme to nicotinamide adenine dinucleotide (NADH). In addition, the arcA gene was deleted that resulted in the inhibition of the expression of citric acid cycle genes under limited aeration conditions. As a consequence, the biomass production was enhanced by 34% and 1,3-PDO formation was elevated from 9.58 to 16.71 g/L. The production of 1,3-PDO per dry cell weight enhanced by 30% from 2.40 to 3.11 g·L−1·DCW−1. The phenotypic changes in the strains were confirmed through the analyses of redox ratio, ATP levels, and changes in the expression of genes related to citric acid cycle and 1,3-PDO pathway.