초록
<P><B>Abstract</B></P> <P>The pentanol isomers 2-methyl-1-butanol and 3-methyl-1-butanol represent commercially interesting alcohols due to their potential application as biofuels. For a sustainable microbial production of these compounds, <I>Corynebacterium glutamicum</I> was engineered for producing 2-methyl-1-butanol and 3-methyl-1-butanol via the Ehrlich pathway from 2-keto-3-methylvalerate and 2-ketoisocaproate, respectively. In addition to an already available 2-ketoisocaproate producer, a 2-keto-3-methylvalerate accumulating <I>C. glutamicum</I> strain was also constructed. For this purpose, we reduced the activity of the branched-chain amino acid transaminase in an available <I>C. glutamicum</I> <SMALL>L</SMALL>-isoleucine producer (K2P55) via a start codon exchange in the <I>ilvE</I> gene enabling accumulation of up to 3.67g/l 2-keto-3-methylvalerate. Subsequently, nine strains expressing different gene combinations for three 2-keto acid decarboxylases and three alcohol dehydrogenases were constructed and characterized. The best strains accumulated 0.37g/l 2-methyl-1-butanol and 2.76g/l 3-methyl-1-butanol in defined medium within 48h under oxygen deprivation conditions, making these strains ideal candidates for additional strain and process optimization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>C. glutamicum</I> strains for the synthesis of 2- and 3-methyl-1-butanol are available. </LI> <LI> Pentanol synthesizing strains are based on potent <I>C. glutamicum</I> 2-keto acid-producers. </LI> <LI> Nine combinations of decarboxylases and dehydrogenases were tested for production. </LI> <LI> Best performing <I>C. glutamicum</I> strains for pentanol production reported so far. </LI> </UL> </P>