초록
<P><B>Abstract</B></P> <P> <I>Gluconobacter oxydans</I> can be efficiently used to produce 3-hydroxypropionic acid (3-HP) from 1,3-propanediol (1,3-PDO). However, the enzymes involved remain unclear. In this study, transcription analysis of two mutants of strain DSM 2003, obtained by UV-mutagenesis, revealed that membrane-bound alcohol dehydrogenase (mADH) and membrane-bound aldehyde dehydrogenase (mALDH) might be the main enzymes involved. Through deletion and complementation of the genes <I>adh</I>A and <I>aldh</I>, mADH and mALDH were verified as the main enzymes responsible for 3-HP production. Then mALDH was verified as the rate-limiting enzyme in 3-HP production. Since that overexpression of mADH had no effect on 3-HP production, whereas overexpression of mALDH increased 23.6% 3-HP production. Finally, the 3-HP titer of 45.8 g/L and the highest productivity 1.86 g/L/h were achieved when the two mutants DSM 2003/<I>adh</I>AB and DSM 2003/<I>aldh</I> were mixed at a ratio of 1:2 (cell density) and used as whole cell catalysts for 3-HP production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> qRT-PCR results showed that mADH and mALDH involved in 3-HP generation. </LI> <LI> Gene deletion/complement confirmed that mADH and mALDH were vital to produce 3-HP. </LI> <LI> Gene overexpression suggested mALDH as rate-limiting enzyme in 3-HP producing. </LI> <LI> Using mixed cells overexpressing mADH or mALDH, improved 3-HP productivity. </LI> </UL> </P>