Updated CV and FTP location. Organisms respond to environmental stress by altering their pattern of protein expression , as an alternative to growing in stressful conditions. A strain of Meyerozyma guilliermondii resistant to manganese was isolated from a sample of water collected from a mine drainage in southeastern Minas Gerais (Brazil), demonstrated manganese detoxification capacity. We compared the changes in protein expression in two different conditions, absence and after exposure to excess manganese and used this information to demonstrate the differential expression of proteins in both conditions and try to of explain the resistance of these yeasts to high concentrations of the metal. We utilized high resolution, high mass accuracy proteomics to explore stress alters expression of proteins involved in the oxidative stress in M. guilliermondii. The study of this proteome may help in the understanding of molecular regulatory mechanisms to tolerate excess Mn, and the use of biomass in the bioremediation process.