Within the framework of his PhD project, Ricardo Santos from the NOVA School of Science and Technology (University of Lisbon), will be visiting CQM and present the conference "Dissecting Killer Yeast Systems – From function to diversity", which will be held on 03rd of December 2025, 10h30, at the conference room 0.57 (University of Madeira, Campus da Penteada).
Space is limited, so please be sure to complete your registration as soon as possible.
Abstract:
Killer yeasts are infected with a double-stranded (ds)RNA virus that encodes a toxin (M virus) and a helper virus (L-A virus), both belonging to the Totiviridae family. Although most studies have focused on Saccharomyces cerevisiae and, more recently, Saccharomyces paradoxus, multiple yeast species exhibit killer phenotypes. Despite advances in understanding infection mechanisms and host immunity, these processes remain only partially resolved.
This project aims to compare the functional characteristics of known killer toxins and to screen yeast populations from the Madeira and Azores Archipelagos (Portugal) for the presence of viral killer systems. Each known toxin - K1, K2 and Klus from S. cerevisiae, and K21/K66, K28, K45, K62 and K74 from S. paradoxus - shows a distinct pH activity profile against the sensitive strain S. cerevisiae 5X47. Among the conditions tested, pH 4.5 consistently yielded the strongest killer activity, and will therefore be applied in subsequent oxidative stress assays and transcriptome analyses of toxin-exposed strains.
Of the 17 S. cerevisiae wine strains isolated from Madeira Island, 16 exhibited killer activity, all producing the K2 toxin. However, variation in inhibition halo diameters against sensitive strains (5X47 and BY4741) suggests possible genetic differences either in the viral elements or the host nuclear genome. Ongoing phylogenetic analyses reveal a notable proximity between Madeira yeast populations and those from South Africa, a pattern that echoes historical Portuguese maritime routes and centuries of exchange across the Atlantic. This historical/biological connection provides a unique framework for understanding the dissemination and evolution of killer systems in geographically isolated regions.
These findings highlight the scientific and biotechnological significance of characterizing killer yeast diversity. By integrating functional assays with population genomics, this work expands current knowledge on microbial symbioses and on the evolutionary dynamics of virus–host interactions in natural yeast populations.
About Ricardo Santos:
Ricardo Santos holds a Master’s degree in Cellular and Molecular Biology from the Faculty of Sciences of the University of Porto and a Bachelor’s degree in Biology from the University of Aveiro. His scientific background encompasses biotechnology, microbiology, molecular biology, virology, genetics, bioinformatics, and microbial biochemistry. He has also received international training in advanced molecular biology techniques at Smith College (USA).
His Master’s thesis, “The Yeast Comet Assay: A Study to Optimize the Technique for the Evaluation of DNA Damage Caused by Exposure to Uranium Mine Effluents,” focused on improving the yeast comet assay to assess genotoxicity arising from environmental contaminants. This work strengthened his expertise in DNA damage assessment, fluorescence microscopy, statistical data analysis, and yeast physiology.
Ricardo is currently a fourth-year PhD candidate in Biology, (specialization in Microbiology and Virology), conducting a collaborative research project involving NOVA School of Science and Technology (University of Lisbon), the University of Manchester, Imperial College London, IB2 Lab (Faculty of Sciences of the University of Porto), and the University of Salamanca. His doctoral research, “Investigating Virus–Host Interactions in the Killer Yeast System,” aims to elucidate the molecular mechanisms underlying killer toxin production and activity in Saccharomyces cerevisiae and S. paradoxus. This work integrates molecular biology, transcriptomics, phylogenetics, microbial fermentation, and protein analysis to explore the biotechnological potential of yeast-derived toxins in areas such as winemaking, agriculture, and antimicrobial development. His PhD is funded by the Maria de Sousa Studentship (FCT | 2021.09335.BD).
In addition, Ricardo is the iB2 Lab microorganism curator and a research collaborator in the European project BiomeHealth, which focuses on plant microbiomes and sustainable disease management. Within this project, he investigates toxin-based biocontrol strategies targeting agricultural pathogens, including Erwinia amylovora and Stemphylium vesicarium, and contributes to field sampling and fungal isolation to support plant pathology research.
Space is limited, so please be sure to complete your registration as soon as possible.
Abstract:
Killer yeasts are infected with a double-stranded (ds)RNA virus that encodes a toxin (M virus) and a helper virus (L-A virus), both belonging to the Totiviridae family. Although most studies have focused on Saccharomyces cerevisiae and, more recently, Saccharomyces paradoxus, multiple yeast species exhibit killer phenotypes. Despite advances in understanding infection mechanisms and host immunity, these processes remain only partially resolved.
This project aims to compare the functional characteristics of known killer toxins and to screen yeast populations from the Madeira and Azores Archipelagos (Portugal) for the presence of viral killer systems. Each known toxin - K1, K2 and Klus from S. cerevisiae, and K21/K66, K28, K45, K62 and K74 from S. paradoxus - shows a distinct pH activity profile against the sensitive strain S. cerevisiae 5X47. Among the conditions tested, pH 4.5 consistently yielded the strongest killer activity, and will therefore be applied in subsequent oxidative stress assays and transcriptome analyses of toxin-exposed strains.
Of the 17 S. cerevisiae wine strains isolated from Madeira Island, 16 exhibited killer activity, all producing the K2 toxin. However, variation in inhibition halo diameters against sensitive strains (5X47 and BY4741) suggests possible genetic differences either in the viral elements or the host nuclear genome. Ongoing phylogenetic analyses reveal a notable proximity between Madeira yeast populations and those from South Africa, a pattern that echoes historical Portuguese maritime routes and centuries of exchange across the Atlantic. This historical/biological connection provides a unique framework for understanding the dissemination and evolution of killer systems in geographically isolated regions.
These findings highlight the scientific and biotechnological significance of characterizing killer yeast diversity. By integrating functional assays with population genomics, this work expands current knowledge on microbial symbioses and on the evolutionary dynamics of virus–host interactions in natural yeast populations.
About Ricardo Santos:
Ricardo Santos holds a Master’s degree in Cellular and Molecular Biology from the Faculty of Sciences of the University of Porto and a Bachelor’s degree in Biology from the University of Aveiro. His scientific background encompasses biotechnology, microbiology, molecular biology, virology, genetics, bioinformatics, and microbial biochemistry. He has also received international training in advanced molecular biology techniques at Smith College (USA).
His Master’s thesis, “The Yeast Comet Assay: A Study to Optimize the Technique for the Evaluation of DNA Damage Caused by Exposure to Uranium Mine Effluents,” focused on improving the yeast comet assay to assess genotoxicity arising from environmental contaminants. This work strengthened his expertise in DNA damage assessment, fluorescence microscopy, statistical data analysis, and yeast physiology.
Ricardo is currently a fourth-year PhD candidate in Biology, (specialization in Microbiology and Virology), conducting a collaborative research project involving NOVA School of Science and Technology (University of Lisbon), the University of Manchester, Imperial College London, IB2 Lab (Faculty of Sciences of the University of Porto), and the University of Salamanca. His doctoral research, “Investigating Virus–Host Interactions in the Killer Yeast System,” aims to elucidate the molecular mechanisms underlying killer toxin production and activity in Saccharomyces cerevisiae and S. paradoxus. This work integrates molecular biology, transcriptomics, phylogenetics, microbial fermentation, and protein analysis to explore the biotechnological potential of yeast-derived toxins in areas such as winemaking, agriculture, and antimicrobial development. His PhD is funded by the Maria de Sousa Studentship (FCT | 2021.09335.BD).
In addition, Ricardo is the iB2 Lab microorganism curator and a research collaborator in the European project BiomeHealth, which focuses on plant microbiomes and sustainable disease management. Within this project, he investigates toxin-based biocontrol strategies targeting agricultural pathogens, including Erwinia amylovora and Stemphylium vesicarium, and contributes to field sampling and fungal isolation to support plant pathology research.
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Registration until 02nd of December 2025. |
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Registration form Limited seats available |