초록
<P><B>Abstract</B></P> <P>The marine bacteria <I>Neptunomonas concharum</I> was firstly characterized in 2012 and grew optimally at 37 °C, whereas the other species of <I>Neptunomonas</I> showed a lower range of temperature to grow. In this study, we described the achievement of metabolic engineering of <I>N. concharum</I> for the synthesis of acetoin and <I>meso</I>-2,3-butanediol. First, a series of carbon sources were used to cultivate <I>N. concharum</I>. Acetate and succinate were found to be suitable substrates to support effective cell growth. Second, a general electransformation procedure was developed. The optimized transformation efficiency reached about 3 × 10<SUP>3</SUP> cfu/μg DNA. Third, the heterologous acetoin and <I>meso</I>-2,3-butanediol biosynthesis pathway was functionally expressed in <I>N. concharum</I>. In shake flask cultivation, the titers of acetoin and <I>meso</I>-2,3-butanediol reached 0.11 g/L. Finally, malic enzyme was overexpressed to improve intracellular pyruvate availability, which significantly improved acetoin and <I>meso</I>-2,3-butanediol titers to 0.56 g/L and 0.38 g/L, respectively. Our results demonstrate that <I>N. concharum</I> has a promising potential to manufacture bulk chemicals using acetate as the carbon source.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The marine bacteria <I>Neptunomonas concharum</I> could efficiently utilize acetate. </LI> <LI> A general electransformation procedure was developed for <I>N. concharum</I>. </LI> <LI> Acetoin and <I>meso</I>-2,3-butanediol biosynthesis pathway was functionally expressed. </LI> <LI> The titers of acetoin and <I>meso</I>-2,3-butanediol reached 0.56 g/L and 0.38 g/L, respectively. </LI> </UL> </P>