Direct observation of oxidative stress on the cell wall of Saccharomyces cerevisiae strains with atomic force microscopy

We imaged pores on the surface of the cell wall of three different industri al strains of Saccharomyces cerevisiae using atomic force microscopy. The p ores could be enlarged using 10 mM diamide, an SH residue oxidant that atta cks surface proteins. We found that two strains showed signs of oxidative d amage via changes in density and diameter of the surface pores. We found th at the German strain was resistant to diamide induced oxidative damage, eve n when the concentration of the oxidant was increased to 50 mM. The normal pore size found on the cell walls of American strains had diameters of abou t 200nm. Under conditions of oxidative stress the diameters changed to 400n m. This method may prove to be a useful rapid screening process (45-60 min) to determine which strains are oxidative resistant, as well as being able to screen for groups of yeast that are sensitive to oxidative stress. This rap id screening tool may have direct applications in molecular biology (transf erence of the genes to inside of living cells) and biotechnology (biotransf ormations reactions to produce chiral synthons in organic chemistry.