Effect of the Gene Knock-out and Gene Knock-in on Mannitol Production in .

can be used to produce mannitol by fermentation, but the mannitol productivity is not high. Therefore, in this study modify the chromosome of by genetic methods to obtain high-yield strains of mannitol production. In this study, gene knock-out strains and gene knock-in strains were constructed by a two-step homologous recombination method. The mannitol productivity of the gene (which encodes phosphate acetyltransferase) deleteon strain (Δ::), gene (which encodes fructokinase) deleteon strain (Δ::) and gene (which encodes serine-threonine protein kinase) deleteon strain (Δ::) were all increased compared to the wild type, and the productivity of mannitol for each strain was 84.8%, 83.5% and 84.1% respectively. The mannitol productivity of the gene (which encodes mannitol dehydrogenase) knock-in strains (Δ::, Δ:: and Δ::) was increased to a higher level than that of the single-gene deletion strains, and the productivity of mannitol for each was 96.5%, 88% and 93.2%, respectively. The multi-mutant strain ΔΔΔ::Δ::Δ:: had mannitol productivity of 97.3%. This work shows that multi-gene knock-out and gene knock-in strains have the greatest impact on mannitol production, with mannitol productivity of 97.3% and an increase of 24.7% over wild type. This study used the methods of gene knock-out and gene knock-in to genetically modify the chromosome of . It is of great significance that we increased the ability of Leuconostoc mesenteroides to produce mannitol and revealed its broad development prospects.