초록
<P>Microbial based bioplastics are promising alternatives to petroleum based synthetic plastics due to their renewability and economic feasibility. Glutarate is one of the most potential building blocks for bioplastics. The recent biosynthetic routes for glutarate were mostly based on the <SMALL>l</SMALL>-lysine degradation pathway from <I>Pseudomonas putida</I> that required lysine either by feeding or lysine overproduction <I>via</I> genetic manipulations. Herein, we established a novel glutarate biosynthetic pathway by incorporation of a “+1” carbon chain extension pathway from α-ketoglutarate (α-KG) in combination with α-keto acid decarboxylation pathway in <I>Escherichia coli</I>. Introduction of homocitrate synthase (HCS), homoaconitase (HA) and homoisocitrate dehydrogenase (HICDH) from <I>Saccharomyces cerevisiae</I> into <I>E.？coli</I> enabled “+1” carbon extension from α-KG to α-ketoadipate (α-KA), which was subsequently converted into glutarate by a promiscuous α-keto acid decarboxylase (KivD) and a succinate semialdehyde dehydrogenase (GabD). The recombinant <I>E.？coli</I> coexpressing all five genes produced 0.3 g/L glutarate from glucose. To further improve the titers, α-KG was rechanneled into carbon chain extension pathway <I>via</I> the clustered regularly interspersed palindromic repeats system mediated interference (CRISPRi) of essential genes <I>sucA</I> and <I>sucB</I> in tricarboxylic acid (TCA) cycle. The final strain could produce 0.42 g/L glutarate, which was increased by 40% compared with the parental strain.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/asbcd6/2017/asbcd6.2017.6.issue-10/acssynbio.7b00136/production/images/medium/sb-2017-001367_0006.gif'></P>