초록
<P><B>Abstract</B></P> <P>Biosynthesis of alkanes in microbial foundries offers a sustainable and green supplement to traditional fossil fuels. The dynamic equilibrium of fatty aldehydes, key intermediates, played a critical role in microbial alkanes production, due to the poor catalytic capability of aldehyde deformylating oxygenase (ADO). In our study, exploration of competitive pathway together with multi-modular optimization was utilized to improve fatty aldehydes balance and consequently enhance alkanes formation in <I>Escherichia coli</I>. Endogenous fatty alcohol formation was supposed to be competitive with alkane production, since both of the two routes consumed the same intermediate—fatty aldehyde. Nevertheless, in our case, alkanes production in <I>E. coli</I> was enhanced from trace amount to 58.8mg/L by the facilitation of moderate fatty alcohol biosynthesis, which was validated by deletion of endogenous aldehyde reductase (AHR), overexpression of fatty alcohol oxidase (FAO) and consequent transcriptional assay of <I>aar</I>, <I>ado</I> and <I>adhP</I> genes. Moreover, alkanes production was further improved to 81.8mg/L, 86.6mg/L or 101.7mg/L by manipulation of fatty acid biosynthesis, lipids degradation or electron transfer system modules, which directly referenced to fatty aldehydes dynamic pools. A titer of 1.31g/L alkanes was achieved in 2.5L fed-batch fermentation, which was the highest reported titer in <I>E. coli</I>. Our research has offered a reference for chemical overproduction in microbial cell factories facilitated by exploring competitive pathway.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dynamic equilibrium of fatty aldehydes, key intermediates, played a critical role in microbial alkanes production. </LI> <LI> Alkanes production in <I>E. coli</I> was enhanced by moderately competitive fatty alcohol biosynthesis. </LI> <LI> The transcriptional raito of <I>aar</I>: <I>ado</I>: <I>adhP</I> was around 0.60: 0.21: 0.19 when the titer of alkane production was the highest. </LI> <LI> Alkane production was further improved by multi modular optimization, which directly referenced to fatty aldehydes dynamic pools </LI> <LI> A highest reported titer of 1.31g/L alkanes in <I>E. coli</I> was achieved. </LI> </UL> </P>