Document Type

Article

Author ORCID Identifier

Owen M. Price https://orcid.org/0000-0001-5894-9022

Joan Hevel https://orcid.org/0000-0002-9559-4635

Jixun Zhan https://orcid.org/0000-0003-0200-9183

Journal/Book Title

Applied Microbiology and Biotechnology

Publication Date

12-7-2021

Award Number

NSF, Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET) 2044558

Funder

NSF, Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET)

Publisher

Springer

Volume

106

Abstract

Glycosylation is an effective way to improve the water solubility of natural products. In this work, a novel glycosyltransferase gene (BbGT) was discovered from Beauveria bassiana ATCC 7159 and heterologously expressed in Escherichia coli. The purified enzyme was functionally characterized through in vitro enzymatic reactions as a UDP-glucosyltransferase, converting quercetin to five monoglucosylated and one diglucosylated products. The optimal pH and temperature for BbGT are 35 ℃ and 8.0, respectively. The activity of BbGT was stimulated by Ca2+, Mg2+, and Mn2+, but inhibited by Zn2+. BbGT enzyme is flexible and can glycosylate a variety of substrates such as curcumin, resveratrol, and zearalenone. The enzyme was also expressed in other microbial hosts including Saccharomyces cerevisiae, Pseudomonas putida, and Pichia pastoris. Interestingly, the major glycosylation product of quercetin in E. coli, P. putida, and P. pastoris was quercetin-7-O-β-D-glucoside, while the enzyme dominantly produced quercetin-3-O-β-D-glucoside in S. cerevisiae. The BbGT-harboring E. coli and S. cerevisiae strains were used as whole-cell biocatalysts to specifically produce the two valuable quercetin glucosides, respectively. The titer of quercetin-7-O-β-D-glucosides was 0.34 ± 0.02 mM from 0.83 mM quercetin in 24 h by BbGT-harboring E. coli. The yield of quercetin-3-O-β-D-glucoside was 0.22 ± 0.02 mM from 0.41 mM quercetin in 12 h by BbGT-harboring S. cerevisiae. This work thus provides an efficient way to produce two valuable quercetin glucosides through the expression of a versatile glucosyltransferase in different hosts.

First Page

227

Last Page

245

Comments

This is a post-peer-review, pre-copyedit version of an article published in Applied Microbiology. The final authenticated version is available online at: https://doi.org/10.1007/s00253-021-11716-x

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