Engineering Yarrowia lipolytica for the Synthesis of Glutathione from Organic By-Products.

Diem T H Do,Patrick Fickers

doi:10.3390/microorganisms8040611

Diem T H Do, Patrick Fickers

Open Access

https://doi.org/10.3390/microorganisms8040611

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Journal: Microorganisms	Publication Date: Apr 23, 2020
Citations: 4	License type: CC BY 4.0

Affiliation: Gembloux Agro-Bio Tech, University of Liège

Abstract

Tripeptide glutathione, which plays important roles in many cellular mechanisms, is also a biotechnology-oriented molecule with applications in medicine, food and cosmetic. Here, the engineering of the yeast Yarrowia lipolytica for the production of this metabolite at high titer values from various agro-industrial by-products is reported. The constitutive overexpression of the glutathione biosynthetic genes GSH1 and GSH2 encoding respectively γ-glutamylcysteine synthetase and glutathione synthetase, together with the INU1 gene from Kluyveromyces marxianus encoding inulinase yielded a glutathione titer value and a productivity of 644 nmol/mg protein and 510 µmol/gDCW, respectively. These values were obtained during bioreactor batch cultures in a medium exclusively comprising an extract of Jerusalem artichoke tuber, used as a source of inulin, and ammonium sulfate, used as a nitrogen source.

Highlights

Tripeptide glutathione (γ-l-glutamyl-l-cysteinyl-glycine, GSH) is present in most living cells
In Saccharomyces cerevisiae and other glutathione-containing organisms, GSH is synthesized in a two-step pathway, where glutamate and cysteine are first linked by γ-glutamylcysteine synthetase (EC6322, encoded by GSH1) to form a γ-glutamyl-cysteine dipeptide
Glycine is linked to the dipeptide by glutathione synthetase (EC6323, encoded by GSH2)

Summary

Introduction

Tripeptide glutathione (γ-l-glutamyl-l-cysteinyl-glycine, GSH) is present in most living cells. Glycine is linked to the dipeptide by glutathione synthetase (EC6323, encoded by GSH2). The biotechnological production of GSH can be performed either by enzymatic reactions with purified enzymes or by fermentation using food-grade microorganisms, such as S. cerevisiae. In the latter case, optimizations of both producing strains by evolutionary or metabolic engineering and bioreactor process development have been considered. The productivity of the strains and processes developed to date remain too low for cost-effective production. One reason for this is the high cost of the culture media, which are most often based on pure glucose. A few processes have considered industrial by-products such as sugarcane molasses as alternative carbon sources [2,4]

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