Biosynthesis of (S)-Equol from Soy Whey by Metabolically Engineered Escherichia coli

Zhe Wang, Xiaonan Li, Fidelis Azi, Yiqiang Dai, Zhuang Xu, Lijun Yu, Jianzhong Zhou, Mingsheng Dong, Xiudong Xia*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


(S)-Equol is one of the most bioactive metabolites of the isoflavones with immense nutritional and pharmaceutical value. Soy whey is the major liquid byproduct of the soy product processing industries that is rich in nutrients and (S)-equol biosynthetic precursor daidzin. However, it is usually disposed into the sewage, causing high environmental contamination. Herein, we constructed a recombinant Escherichia coli for the biosynthesis of (S)-equol from soy whey. First, we evaluated daidzin-specific transporters and optimized the anaerobically induced Pnar in the (S)-equol biosynthesis cassette to produce (S)-equol from daidzin. Then, sucrase and α-galactosidase were co-expressed to confer sucrose, stachyose, and raffinose utilization capacity on E. coli. Meanwhile, EIIBCAglc was inactivated to eliminate the daidzin transport inhibition induced by glucose. Finally, combining these strategies and optimizing the fermentation conditions, the optimal strain produced 91.5 mg/L of (S)-equol with a yield of 0.96 mol/mol substrates in concentrated soy whey. Overall, this new strategy is an attractive route to broaden the applications of soy whey and achieve the eco-friendly production of (S)-equol.
Original languageEnglish
Pages (from-to)6110-6119
JournalJournal of Agricultural and Food Chemistry
StatePublished - 11 Apr 2023


  • soy whey
  • (S)-equol
  • daidzin
  • metabolic engineering
  • Escherichia coli


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