SENSITIVITY TO FUEL DIESEL OIL AND CELL-WALL STRUCTURE OF SOME SCENEDESMUS (CHLOROCOCCALES) STRAINS

Sensitivity of three Scenedesmus strains exposed to aqueous fuel-oil e xtract (AFOE) is strongly strain-dependent: S. qu- adricauda is the mo st resistant, S. armatus moderately tolerant whereas the most sensitiv e appears to be S. microspina. The sensitivity of tested species incre ases parallel with decreasing of cell size and cell number in coenobiu m. The values of the cell surface/cell volumes ratios only partly expl ain the above relationships. Electron microscope investigations reveal that the sensitivity may depend on cell wall structure of the strains . Cell wall of all here investigated strains is built of two layers: t he inner so-called cellulosic layer and the outer one showing a three- laminar structure (TLS). The latter contains an acetolysis-resistant b iopolymer (ARE). These two layers are similar in thickness in the thre e strains tested, but the surface of Scenedesmus is covered with vario us epistructures that are characteristic of strains. Some of them as t he tightly fitting warty layer of S. armatus and especially the loosel y fitting reticulate layer of S. quadricauda may contribute to lower p ermeability of cell wall. The structure of the rosettes also appears t o be correlated with the sensitivity of strains. Presence of invaginat ions of plasmalemma in areas under rosettes indicates their role in tr ansport processes inside/outside the cells.