Physiological characterization of a new thermotolerant yeast strain isolated during Brazilian ethanol production, and its application in high-temperature fermentation

Cleiton D Prado,Jonas P Souza,Iran Malavazi,Anderson F Cunha,Mateus H R Alves,Flávia B Sgobbi,Diele P Procópio,Thiago O Basso,Reinaldo Giudici,João P M O Da Silva,Gustavo P L Mandrujano,Hosana R Novaes,Kevy P Eliodório,Gabriel C G Cunha

doi:10.1186/s13068-020-01817-6

Cleiton D Prado, Jonas P Souza + Show 12 more

Open Access

https://doi.org/10.1186/s13068-020-01817-6

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Abstract

BackgroundThe use of thermotolerant yeast strains can improve the efficiency of ethanol fermentation, allowing fermentation to occur at temperatures higher than 40 °C. This characteristic could benefit traditional bio-ethanol production and allow simultaneous saccharification and fermentation (SSF) of starch or lignocellulosic biomass.ResultsWe identified and characterized the physiology of a new thermotolerant strain (LBGA-01) able to ferment at 40 °C, which is more resistant to stressors as sucrose, furfural and ethanol than CAT-1 industrial strain. Furthermore, this strain showed similar CAT-1 resistance to acetic acid and lactic acid, and it was also able to change the pattern of genes involved in sucrose assimilation (SUC2 and AGT1). Genes related to the production of proteins involved in secondary products of fermentation were also differentially regulated at 40 °C, with reduced expression of genes involved in the formation of glycerol (GPD2), acetate (ALD6 and ALD4), and acetyl-coenzyme A synthetase 2 (ACS2). Fermentation tests using chemostats showed that LBGA-01 had an excellent performance in ethanol production in high temperature.ConclusionThe thermotolerant LBGA-01 strain modulates the production of key genes, changing metabolic pathways during high-temperature fermentation, and increasing its resistance to high concentration of ethanol, sugar, lactic acid, acetic acid, and furfural. Results indicate that this strain can be used to improve first- and second-generation ethanol production in Brazil.

Highlights

The use of thermotolerant yeast strains can improve the efficiency of ethanol fermentation, allowing fermentation to occur at temperatures higher than 40 °C
Identification and molecular genotyping of a thermotolerant yeast strain for use in high‐temperature fermentation for ethanol production To obtain specialized yeast for ethanol production in Brazil, several attributes need to be considered and evaluated, such as ability to produce high yields of ethanol, high cell viability, and tolerance to stressors produced during ethanol production
The Laboratory of Biochemistry and Applied Genetics of the Federal University of São Carlos (LBGAUFSCar) has been isolating yeasts from ethanol production since 2009, which have been deposited in the Laboratory of biochemistry and applied genetics (LBGA) strain collection

Summary

Results

We identified and characterized the physiology of a new thermotolerant strain (LBGA-01) able to ferment at 40 °C, which is more resistant to stressors as sucrose, furfural and ethanol than CAT-1 industrial strain. This strain showed similar CAT-1 resistance to acetic acid and lactic acid, and it was able to change the pattern of genes involved in sucrose assimilation (SUC2 and AGT1). Fermentation tests using chemostats showed that LBGA-01 had an excellent performance in ethanol production in high temperature

Conclusion

Background

Results and discussion

Material and methods