Enhanced production of l-serine by deleting sdaA combined with modifying and overexpressing serA in a mutant of Corynebacterium glutamicum SYPS-062 from sucrose

• Published in: Biochemical engineering journal Vol. 103; pp. 60 - 67
• Main Authors: Xu, Guoqiang, Zhu, Qinjian, Luo, Yuchang, Zhang, Xiaojuan, Guo, Wen, Dou, Wenfang, Li, Hui, Xu, Hongyu, Zhang, Xiaomei, Xu, Zhenghong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2015
• Subjects: Amino Acids; Biosynthesis; Fermentation; Microbial growth; Mutagenesis; Sucrose; Microbial growth; Biosynthesis; Mutagenesis; Sucrose; Fermentation; Amino Acids
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2015.06.009

•Sucrose was found to be favorable for cell growth and l-serine accumulation.•The resulting mutant accumulated 65.4% more l-serine (11.0±0.25g/L).•This mutant harbors a better ability to consume sucrose.•serA modification led to dramatically increase in l-serine production.•The key to enhance l-serine production was the removal of the feedback inhibition. The direct fermentative production of l-serine using Corynebacterium glutamicum from renewable biomass attracts increasing attention. This study was designed to enhance l-serine production in a wild-type C. glutamicum SYPS-062 by using random mutagenesis, optimization of media, and metabolic engineering. The resulting mutant, C. glutamicum SYPS 062-33a, accumulated 65.4% more l-serine (11.0±0.25g/L) and exhibited higher growth and production of other amino acids (such as l-alanine, l-valine) compared with the parent strain. Interestingly, this mutant harbors a better ability to consume sucrose, which is the main composition of economical molasses. To further enhance l-serine production, single sdaA deletion and serA modification was performed, which led to 14.76±0.82g/L and 19.42±1.20g/L l-serine, respectively. While double sdaA deletion and serA modification led to 21.27±1.87g/L l-serine. In addition, when the modified serA gene was overexpressed in C. glutamicum SYPS-062-33aΔSS, the resultant strain accumulated 24.43±0.95g/L and 21.6±1.2g/L l-serine in flask and 5-L bioreactor, respectively. Unlike the previous finding, this study demonstrated that the key to further enhance l-serine production may be the removal of the feedback inhibition of PGDH by l-serine in a high l-serine-producing strain C. glutamicum SYPS-062-33a.