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Engineering Pichia pastoris to improve S‐adenosyl‐ l ‐methionine production using systems metabolic strategies
Author(s) -
Qin Xiulin,
Lu Junjie,
Zhang Yin,
Wu Xiaole,
Qiao Xuefeng,
Wang Zhipeng,
Chu Ju,
Qian Jiangchao
Publication year - 2020
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.27300
Subject(s) - pichia pastoris , titer , fermentation , cystathionine beta synthase , metabolic engineering , methionine , biochemistry , chemistry , homocysteine , pichia , yeast , gene , biology , recombinant dna , amino acid , genetics , virus
S‐adenosyl‐ l ‐methionine (SAM) is a highly valued chemical that can be used as a dietary supplement and has been used to treat depression, osteoarthritis, and liver problems as well. We adopted systems metabolic engineering strategies to improve SAM production in a high‐producing strain (GS115/DS56). First, the cystathionine β‐synthase gene CYS4 was downregulated using a weak promoter P G12 to reduce the removal of homocysteine from SAM cycle, thus leading to a 48.8% increase in the SAM titer (1.68 g/L) from the strain G12‐CBS, while preventing cysteine auxotrophy induced by deletion of this essential gene. Subsequently, the SAM titer of G12‐CBS was improved to 13.01 g/L in 15‐L fed‐batch fermentation using the optimal l ‐methionine feeding strategy. Finally, based on comparative transcriptomics, five genes were chosen and overexpressed for further enhancement of SAM production. Among them, GDH2 and ACS2 exhibited positive effects, and the additional overexpression of GDH2 led to a 52.3% increase of titer (2.71 g/L) in shake flask culture. Therefore, the engineered Pichia pastoris strains can be utilized in industrial production of SAM using a simple and cost‐effective process, and these approaches could be employed for improving the production of other chemicals by P. pastoris .