Effects of Several Nonionic and Anionic Surfactants on Cucumber Protoplasts*

The effects of four nonionic and two anionic surfactants on cucumber protoplasts were examined by light and electron microscopy. Two nonionic surfactants, polyoxyethylene (POE) (n=10) nonylphenylether and POE (n=5) laurylether, caused swelling of protoplasts, followed by their bursting. The bursting gave more destructive effects preferentially on lamellar structures of chloroplasts than the swelling. Two other nonionic surfactants, POE (n=10) oleylether and POE (n=20) stearylether, appeared to have little effects on the morphology of protoplasts by light microscopy, but electron microscopy revealed abundant spotty and linear, electron-transparent spaces in treated chloroplasts. Protoplasts were drastically destroyed by two anionic surfactants, Na-dioctylsulfosuccinate and Na-dibutylnaphthalene-sulfonate. Their entire structure was almost completely disrupted by these surfactants at 1000ppm. Among organelles, chloroplasts were preferentially sensitive to all test surfactants. All of nonionic surfactants caused at least some cytological changes in chloroplasts at their respective, critical micelle concentrations (cmc), while anionic surfactants worked heavy damages to chloroplasts and other organelles at concentration lower than cmc. The effect of each surfactant seemed to depend on its organelles, membranes of single organelle and molecular structure in the microscopic observation.