Effect of overexpressed puuC on 3-HP production by fermented glycerol of Klebsiella pneumoniae
To augment the 3-hydroxypropionic acid(3-HP)production capability in Klebsiella pneumoniae HD79,the aldehyde dehydrogenase gene puuC was cloned and overexpressed.This overexpression was investigated for its influence on aldehyde dehydrogenase(ALDH)activity and 3-HP production in the glycerol reduction pathway.The experiment confirms successful enhancement of a recombinant strain,K.pneumoniae HD79-T,which shows improved 3-HP production due to the overexpression of puuC.The maximum 3-HP yield from the HD79-T strain is(2.05±0.03)g·L-1,displaying a striking increase of 39.46%compared to the typical K.pneumoniae HD79 yield((1.47±0.02)g·L-1).The relative gene expression levels in the HD79-T strain,including puuC,the glycerol dehydrase gene dhaB,and the 1,3-propanediol oxidoreductase gene dhaT,amplifiy by multiples of 94.35,1.72,and 1.35 respectively.Correspondingly,enzyme activities of ALDH,glycerol dehydrase(GDHt),and 1,3-propanediol oxidoreductase(1,3-PDOR)rise by 27.40%,18.85%,and 5.10%respectively.Thus,the HD79-T strain develops here substantially enhanced ALDH enzyme activity,rendering it a potential strain for effective glycerol fermentation to yield 3-HP.