Affiliation:
1. Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences Tianjin China
2. National Technology Innovation Center of Synthetic Biology Tianjin China
3. School of Life Science, Bengbu Medical College Bengbu China
Abstract
AbstractAlthough a high titre of malic acid is achieved by filamentous fungi, by‐product succinic acid accumulation leads to a low yield of malic acid and is unfavourable for downstream processing. Herein, we conducted a series of metabolic rewiring strategies in a previously constructed Myceliophthora thermophila to successfully improve malate production and abolish succinic acid accumulation. First, a pyruvate carboxylase CgPYC variant with increased activity was obtained using a high‐throughput system and introduced to improve malic acid synthesis. Subsequently, shifting metabolic flux to malate synthesis from mitochondrial metabolism by deleing mitochondrial carriers of pyruvate and malate, led to a 53.7% reduction in succinic acid accumulation. The acceleration of importing cytosolic succinic acid into the mitochondria for consumption further decreased succinic acid formation by 53.3%, to 2.12 g/L. Finally, the importer of succinic acid was discovered and used to eliminate by‐product accumulation. In total, malic acid production was increased by 26.5%, relative to the start strain JG424, to 85.23 g/L and 89.02 g/L on glucose and Avicel, respectively, in the flasks. In a 5‐L fermenter, the titre of malic acid reached 182.7 g/L using glucose and 115.8 g/L using raw corncob, without any by‐product accumulation. This study would accelerate the industrial production of biobased malic acid from renewable plant biomass.
Funder
National Natural Science Foundation of China
Youth Innovation Promotion Association of the Chinese Academy of Sciences
Subject
Applied Microbiology and Biotechnology,Biochemistry,Bioengineering,Biotechnology