Succinic acid production from softwood with genome‐edited <i>Corynebacterium glutamicum</i> using the CRISPR‐Cpf1 system
Dae-Seok Lee, Eun Jin Cho, Dinh‐Truong Nguyen, Younho Song, Jihye Chang, Hyeun‐Jong Bae
Abstract
Abstract Corynebacterium glutamicum is a useful microbe that can be used for producing succinic acid under anaerobic conditions. In this study, we generated a knock‐out mutant of the lactate dehydrogenase 1 gene ( ΔldhA‐6 ) and co‐expressed the succinic acid transporter (Psod:SucE‐ ΔldhA ) using the CRISPR‐Cpf1 genome editing system. The highly efficient HPAC (hydrogen peroxide and acetic acid) pretreatment method was employed for the enzymatic hydrolysis of softwood ( Pinus densiflora ) and subsequently utilized for production of succinic acid. Upon evaluating a 1%–5% hydrolysate concentration range, optimal succinic acid production with the ΔldhA mutant was achieved at a 4% hydrolysate concentration. This resulted in 14.82 g L −1 succinic acid production over 6 h. No production of acetic acid and lactic acid was detected during the fermentation. The co‐expression transformant, [Psod:SucE‐ ΔldhA ] produced 17.70 g L −1 succinic acid in 6 h. In the fed‐batch system, 39.67 g L −1 succinic acid was produced over 48 h. During the fermentation, the strain consumed 100% and 73% of glucose and xylose, respectively. The yield of succinic acid from the sugars consumed was approximately 0.77 g succinic acid/g sugars. These results indicate that the production of succinic acid from softwood holds potential applications in alternative biochemical processes.