Herbicide glufosinate inhibits yeast growth and extends longevity during wine fermentation

Beatriz Vallejo,Agustín Aranda,Emilia Matallana,Helena Orozco,Cecilia Picazo

doi:10.1038/s41598-017-12794-6

Abstract

Glufosinate ammonium (GA) is a widely used herbicide that inhibits glutamine synthetase. This inhibition leads to internal amino acid starvation which, in turn, causes the activation of different nutrient sensing pathways. GA also inhibits the enzyme of the yeast Saccharomyces cerevisiae in such a way that, although it is not used as a fungicide, it may alter yeast performance in industrial processes like winemaking. We describe herein how GA indeed inhibits the yeast growth of a wine strain during the fermentation of grape juice. In turn, GA extends longevity in a variety of growth media. The biochemical analysis indicates that GA partially inhibits the nutrient sensing TORC1 pathway, which may explain these phenotypes. The GCN2 kinase mutant is hypersensitive to GA. Hence the control of translation and amino acid biosynthesis is required to also deal with the damaging effects of this pesticide. A global metabolomics analysis under winemaking conditions indicated that an increase in amino acid and in polyamines occurred. In conclusion, GA affects many different biochemical processes during winemaking, which provides us with some insights into both the effect of this herbicide on yeast physiology and into the relevance of the metabolic step for connecting nitrogen and carbon metabolism.

Highlights

Wine yeast faces many adverse conditions when grape juice fermentation starts[1]
This paper explores the impact of herbicide glufosinate ammonium on wine yeast performance and its ways of action
It extended longevity in a variety of environments. This herbicide strongly impacts yeast physiology, and was used as a good tool to study the relevance of the affected metabolic reaction, the inhibition of glutamine synthetase (GS), a key step is ammonium assimilation, which, together with the glutamate synthase reaction, connected carbon and nitrogen metabolisms

Summary

Introduction

Wine yeast faces many adverse conditions when grape juice fermentation starts[1]. High sugar concentration, low pH and oxygen are the stress conditions naturally imposed to yeasts. 3-Amino-1,2,4-triazole (3-AT) is the component of herbicide amitrol and, thanks to its inhibition of histidine biosynthesis, it has been widely used in research to study the mechanisms of amino acid starvation. It has a potential impact on most grape fungal microbiota[9]. Methionine sulfoximine (MSX) blocks glutamine synthase (GS), a central reaction in nitrogen assimilation in yeast that synthesizes glutamine from glutamic acid and free ammonium This glutamine starvation triggers the inhibition of the Target Of Rapamycin (TOR) kinase[16]. A metabolomics analysis that gives us hints on the interconnection between carbon and nitrogen metabolism in wine yeast has been performed

Methods

Results

Conclusion