The Involvement Of Antioxidant In Saccharomyces Cerevisiae Aluminum Tolerance

Metal contamination is now becoming one of the most serious worldwide environmental problems. Aluminum (Al) was found in small amounts in all organisms, and was confirmed to do harm to human health and inhibit the growth of plants in acid soil. During the process in studying Al toxicity to the orgaiusms, people changed the opinion that Al was innoxious in biosystems, and became more aware of the importance of the mechanisms of Al-toxicity and Al-tolerance in environmental and life sciences.We reviewed four mechanisms of Al toxicity and tolerance in microorganisms, including (1)excreting organic acids to chelate Al³⁺, (2)overexpression Mg²⁺ transporter protein to transport Mg²⁺ into the cell ,(3)segregating Al³⁺ in vacuole by F₁F₀-ATPase and V-ATPase to eliminate the toxicity of Al³⁺ and (4)regulating the oxidative stress to modify the Al toxicity and tolerance mechanism in microorganisms.In this paper, we studied the Al toxicity and tolerance mechanism in yeast Saccharomyces cerevisiae with the wild strain CY4 and gshl mutant CY8, and got these results: (1)Al³⁺ indirectly induced the increase of reactive oxygen species in yeast cell. Under the high concentration of Al³⁺, the ROS levels increased obviously both in wild strain CY4 and gshl mutant CY8, but the increase of ROS in gsh1 mutant CY8 was more than that of wild strain CY4 when treated with a low Al³⁺ concentration.(2)The SOD activity and trehalose content in the yeast cells increased obviously under the Al³⁺ stress, which probably contributed to the enhancement of Al³⁺ tolerance in yeast.(3)The analysis result of GSH content in the yeast cell indicated that, the GSH content in yeast cell treated with Al³⁺was less than that of the yeast cell without Al³⁺ treatment, which revealed that Al³⁺ decreased the GSH regeneration. However, the GSH content in the yeast cell treated with a high concentration of Al³⁺ was more than that of the yeast cell treated with a low concentration of Al³⁺, which revealed that Al³⁺was not the only factor in regulating the GSH synthesis, and it was probably regulated by other factors such as ROS. Additionally, the increase of GSH content in yeast cell could improve their Al³⁺ tolerance.