Blocking mitophagy does not significantly improve fuel ethanol production in bioethanol yeast Saccharomyces cerevisiae
Journal article, 2022

Ethanolic fermentation is frequently performed under conditions of low nitrogen. In Saccharomyces cerevisiae, nitrogen limitation induces macroautophagy, including the selective removal of mitochondria, also called mitophagy. Shiroma and co-workers (2014) showed that blocking mitophagy by deletion of the mitophagy specific gene ATG32 increased the fermentation performance during the brewing of Ginjo sake. In this study, we tested if a similar strategy could enhance alcoholic fermentation in the context of fuel ethanol production from sugarcane in Brazilian biorefineries. Conditions that mimic the industrial fermentation process indeed induce Atg32-dependent mitophagy in cells of S. cerevisiae PE-2, a strain frequently used in the industry. However, after blocking mitophagy, no significant differences in CO2 production, final ethanol titres or cell viability were observed after five rounds of ethanol fermentation, cell recycling and acid treatment, as commonly performed in sugarcane biorefineries. To test if S. cerevisiae’s strain background influences this outcome, cultivations were carried out in a synthetic medium with strains PE-2, Ethanol Red (industrial) and BY (laboratory), with and without a functional ATG32 gene, under oxic and oxygen restricted conditions. Despite the clear differences in sugar consumption, cell viability and ethanol titres, among the three strains, we could not observe any significant improvement in fermentation performance related to the blocking of mitophagy. We conclude with caution that results obtained with Ginjo sake yeast is an exception and cannot be extrapolated to other yeast strains and that more research is needed to ascertain the role of autophagic processes during fermentation.

Brazilian Fuel Ethanol Fermentation

Mineral Medium





Kevy Pontes Eliodorio

University of Sao Paulo (USP)

Gabriel Caetano de Gois E. Cunha

University of Sao Paulo (USP)

Brianna A. White

University of Sheffield

Demisha H. M. Patel

University of Sheffield

Fangyi Zhang

University of Sheffield

Ewald H. Hettema

University of Sheffield

Thiago Olitta Basso

University of Sao Paulo (USP)

Andreas Karoly Gombert

State University of Campinas

Vijayendran Raghavendran

University of Sheffield

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Applied and Environmental Microbiology

0099-2240 (ISSN) 1098-5336 (eISSN)

Vol. 88 5 e02068-21

Driving Forces

Sustainable development

Subject Categories

Cell and Molecular Biology


Areas of Advance



Basic sciences





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