Improvement of L‐lysine production combines with minimization of by‐products synthesis in Corynebacterium glutamicum

Abstract BACKGROUND Corynebacterium glutamicum was engineered for improvement of L‐lysine production and minimization of by‐products synthesis by genetically engineering. RESULTS The most promising recombinant strain C. glutamicum Lys9 produced 62.1 mmol L‐1 L‐lysine with substrate‐specific yield (YP/S) of 0.28 mol per mol of glucose in shake flasks fermentation, whereas parental strain showed more than four times lower L‐lysine production and more than 10 times lower biomass‐specific yield (YP/X) than that of C. glutamicum Lys9. L‐lysine production and cell growth were drastically decreased by isocitrate dehydrogenase (ICD) attenuation in aceE deletion strains, indicating that down‐regulation of ICD activity in aceE deletion strains adversely affects L‐lysine production. In fed‐batch fermentation, C. glutamicum Lys9 produced 526 mmol L‐1 L‐lysine, i.e. 96.8 g L‐1 L‐lysine‐HCl with high yield of 0.422 mol per mol of glucose and productivity of 2.69 g L‐1 h‐1. Corynebacterium glutamicum Lys9 was devoid of any detectable L‐alanine and L‐lactate synthesis. CONCLUSION Superior to classical producers to some degree, C. glutamicum Lys9 is more adaptable for industrial L‐lysine production. In addition to L‐lysine, pyruvate, oxaloacetate (OAA) and L‐valine were produced by C. glutamicum Lys9, suggesting further optimization to improve L‐lysine production by engineering the L‐lysine and/or NADPH biosynthetic pathway. © 2013 Society of Chemical Industry