Abstract: The effect of CO2 stress treatment on cell membrane permeability of Pichia membranaefaciens was studied， by measuring the conductivity， the concentration of nucleic acid， protein， and malondialdehyde(MDA)，and the fluorescence intensity before and after treatment. The results showed that the conductivity， the concentration of nucleic acid， protein， fluorescence intensity， and MDA content in the broth increased gradually after CO2 stress. The results indicated that CO2 stress caused the increasing membrane permeability of Pichia membranaefaciens， which might be an important cause of cell death．

Key words: CO2 stress, Pichia membranifaciens, permeability of cell membrane