| 초록 |
3-Hydroxypropionic acid (3-HP) has vast applications in the synthesis of industrially important chemicals. We have demonstrated the biological production of 3-HP at 38.5 g/L from glycerol by recombinant Escherichia coli strains with exogenous addition of expensive coenzyme B12. To overcome the limitation of coenzyme B12, Klebsiella pneumoniae, a natural coenzyme B12 producer was genetically modified to synthesise 3-HP. In one approach, coproduction of 1,3-propanediol (1,3-PDO) and 3-HP at 16 ± 1 g/L each in 24 h was demonstrated by developing a recombinant K. pneumoniae ∆dhaT overexpressing aldehyde dehydrogenase. In another approach, a recombinant K. pneumoniae strain devoid of glycerol kinase (glpK) and 1,3-propanediol oxidoreductase (dhaT) genes resulted in ~22 ± 2 g/L 3-HP in presence of nitrate under anaerobic conditions. To improve the yield of 3-HP, the recombinant K. pneumoniae ∆dhaT was further modified by deleting yqhD gene encoding NADPH dependent hypothetical oxidoreductase. This strain under controlled aeration condition produced ~28 g/L 3-HP with 40% yield on glycerol. |
