(599b) Increased Expression of Pyruvate Carboxylase and Biotin Protein Ligase Increases Lysine Production in a Biotin Prototrophic Corynebacterium Glutamicum Strain

Lysine is produced in a fermentation process using Corynebacterium glutamicum, and even though production strains have been improved for decades, there is still room for further optimization. Previously, many of the original C. glutamicum production strains were developed through classical means. Due to the rapid development of molecular biology and omics technology, the psysiology of C. glutamicum could be more deeply characterized and metabolic engineering and synthetic biology could also be applied more directly and systematically.  This project is focussing on the investigation and elimination of the metabolic limitations in lysine production. Our recent research efforts have been directed towards engineering this cell factory to consume more sustainable carbon source or cheaper medium without sacrificing productivity and yield. C. glutamicum is naturally a biotin auxotroph and biotin as an expensive eternal compound is required for cell growth. Here, we introduced a plasmid encoding biotin biosynthetic genes into C. glutamicum to create a biotin prototroph, which could achieve about 80% maximum growth rate in biotin-free medium compared to in biotin-supplemented medium. Based on this biotin prototrophy, and in combination with the over-expression of pyruvate carboxylase and biotin protein ligase, the lysine yield increased to 55% higher than the reference strain (AHP-3).