Transmission electron microscope analysis upon growth of lead acetate treated microalga, Dunaliella sp

The objectives of the present research were to evaluate the effect of lead acetate on the growth of microalgae Dunaliella sp. and to its structure through Transmission Electron Microscope. Dunaliella sp. used in this study was taken from stock available at the Aquaculture Technology Laboratory of the Faculty of Fisheries and Marine Sciences, Sam Ratulangi University, Manado, Indonesia. The cell of Dunaliella sp. is motile and its shapes vary from ellipse to cylinder. Cell length varies depending on the shape of the cell. Radial symmetry shape has about 2.8-40 µm. Seawater used as the culture medium was taken from clean sea waters and far from settlements. Sea water was filtered using 0.45 µm filter paper with the help of an aspirator, then diluted with distilled water until it reached a salinity of 20 ppt. Microalgae Dunaliela sp. were cultured using walne medium in the culture chamber with a temperature of 25° C, salinity of 20 ppt with 20-watt tube light irradiation. Algae harvesting was done when the algal density had reached the exponential phase by calculating the density of microalgae every day using a haemocytometer assisted by a light microscope. After the algae reached exponential density, the samples were treated with lead acetate at 30, 50 and 80 ppm. After harvesting, the algae were centrifuged and subjected to the Transmission Electron Microscope (TEM) analysis. The specimens were prepared through a standard preparation of Plastic Block (Resin) consisted of fixation, dehydration, infiltration, embedding and curing. The density of microalgae was calculated using a haemocytometer under a light microscope. The research results showed that the density of Dunaliella sp. was not significantly different conidering different concentrations of lead acetate. The density of Dunaliella sp. had no relationship with the cell structure of each concentration of lead acetate used. Transmission Electron Microscope analysis showed the cell structure of Dunaliella sp. treated with lead acetate was damaged at the cell membrane and many cells were dead and damaged as compared to control.