초록
<P><B>Abstract</B></P> <P>The amino acid lysine is among the world’s most important biotechnological products, and enabling its manufacture from the most attractive new materials is an ever-present challenge. In this study, we describe a cell factory of <I>Corynebacterium glutamicum</I>, which produces lysine from mannitol. A preliminary mutant <I>C. glutamicum</I> SEA-1 obtained by the deletion of the mannitol repressor MtlR in the glucose-based, lysine-producing strain <I>C. glutamicum</I> LYS-12 produced only small amounts of lysine. This limitation was due to a significant accumulation of fructose and a limited NADPH supply, which caused a low flux of only 6% into the oxidative pentose phosphate (PP) pathway. Subsequent expression of fructokinase slightly increased production but failed to substantially redirect the flux from the Emden-Meyerhof-Parnas (EMP) pathway to the PP pathway. This suggested the design of <I>C. glutamicum</I> SEA-3, which overexpressed the NADP-dependent glyceraldehyde 3-phosphate dehydrogenase GapN from <I>Streptococcus mutans</I> and coupled the EMP pathway flux to NADPH formation. When grown on mannitol, the SEA-3 strain had a lysine yield of 0.24 mol mol<SUP>-1</SUP> and a specific productivity of 1.3 mmol g<SUP>-1</SUP> h<SUP>-1</SUP>, approximately 60% and 75% higher, respectively, than those of the basic producer SEA-1. A computational pathway analysis revealed that this design would potentially enable a lysine yield of 0.9 mol mol<SUP>-1</SUP>, providing room for further development. Our findings open new avenues for lysine production from marine macroalgae, which is farmed globally as an attractive third-generation renewable resource. Mannitol is a major constituent of these algae (up to 30% and higher) and can be easily extracted from their biomass with hot water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First cell factory of <I>Corynebacterium glutamicum</I>, producing lysine from mannitol. </LI> <LI> Mannitol-grown cells exhibit extremely low pentose phosphate pathway </LI> <LI> Heterologous fructokinase and NADPH-coupled glycolysis drive the lysine pathway </LI> <LI> Enables production from seaweed, a mannitol containing third-generation renewable </LI> </UL> </P>