초록
<P><B>Abstract</B></P> <P>Engineered microbes offer the opportunity to design and implement artificial molecular pathways for renewable production of tailored chemical commodities. Targeted biosynthesis of odd-chain fatty alcohols is very challenging in microbe, due to the specificity of fatty acids synthase for two-carbon unit elongation. Here, we developed a novel strategy to directly tailor carbon number in fatty aldehydes formation step by incorporating α-dioxygenase (αDOX) from <I>Oryza sativa</I> (rice) into <I>Escherichia coli</I> αDOX oxidizes C<SUB> <I>n</I> </SUB> fatty acids (even-chain) to form C<SUB> <I>n−</I>1</SUB> fatty aldehydes (odd-chain). Through combining αDOX with fatty acyl–acyl carrier protein (-ACP) thioesterase (TE) and aldehyde reductase (AHR), the medium odd-chain fatty alcohols profile (C<SUB>11</SUB>, C<SUB>13</SUB>, C<SUB>15</SUB>) was firstly established in <I>E. coli</I>. Also, medium even-chain alkanes (C<SUB>12</SUB>, C<SUB>14</SUB>) were obtained by substitution of AHR to aldehyde decarbonylase (AD). The titer of odd-chain fatty alcohols was improved from 7.4mg/L to 101.5mg/L in tube cultivation by means of fine-tuning endogenous fatty acyl-ACP TE (TesA′), αDOX, AHRs and the genes involved in fatty acids metabolism pathway. Through high cell density fed-batch fermentation, a titer of 1.95g/L odd-chain fatty alcohols was achieved, which was the highest reported titer in <I>E. coli</I>. Our system has greatly expanded the current microbial fatty alcohols profile that provides a new brand solution for producing complex and desired molecules in microbes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metabolic engineering of <I>E. coli</I> to produce odd-chain fatty alcohol (C<SUB>11</SUB>, C<SUB>13</SUB>, C<SUB>15</SUB>). </LI> <LI> Demonstrated tailored production of desired medium odd chain fatty alcohols. </LI> <LI> Tuning gene expression levels in up- and down-stream pathway to improve production. </LI> <LI> A highest reported titer of 1.95g/L fatty alcohols in <I>E. coli</I> was achieved. </LI> </UL> </P>