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

doi:10.1021/acs.jafc.3c00439

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

J Agric Food Chem. 2023 Apr 11. doi: 10.1021/acs.jafc.3c00439. Online ahead of print.

Authors

Zhe Wang^{1

2}, Xiaonan Li^{1

3}, Fidelis Azi⁴, Yiqiang Dai^{1

2}, Zhuang Xu^{1

3}, Lijun Yu¹, Jianzhong Zhou^{1

3

5}, Mingsheng Dong², Xiudong Xia^{1

3

5}

Affiliations

¹ Institute of Agro-Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
² College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
³ School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
⁴ Department of Chemical Engineering, Guangdong Technion-Israel Institute of Technology, Shantou 515063, China.
⁵ Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base, Ministry of Science and Technology, Nanjing 210014, China.

PMID: 37038970
DOI: 10.1021/acs.jafc.3c00439

Abstract

(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 P_nar 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, EIIBCA^glc 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.

Keywords: (S)-equol; Escherichia coli; daidzin; metabolic engineering; soy whey.