Effects of zinc, mercury and tin to the antioxidant enzyme activity on Arthrospira platensis Gomont

Metal pollution as a result of the technological and industrial activities can reach to hazardous level at food chain. Fresh water ecosystems have been damaged exceedingly from metal contamination. Especially the algae that constitute the first step of the food chain in water, are affected by metal stress and this situation affects the species composition of ecosystems and the top of the food chain. Algae are used in large-scale both in ecosystem monitoring studies and water eco-toxicology studies that conducted to determine the maximum tolerated concentrations of metals. Due to the metal stress, changes in the algae cells, low tolerance and high tolerance algae are determined in these studies. Algae cells have developed a wide variety of tolerance mechanisms against metal stress. One of these metal tolerance mechanisms in algae is that depending on the organization of antioxidant enzymes against metal effective oxidative stress. In this study, A .platensis was exposed to different concentrations of heavy metals such as zinc, tin and mercury. In this manner, changes in chlorophyll-a concentration biomass, antioxidant enzymes activites (SOD, APOD, GR) were determined. The increase in the level of heavy metals have been found to cause cellular damage. Zinc, mercury and tin applications decreased both biomass and chlorophyll-a content in a time and concentration dependent manner when compared to controls. According to our results, tin was found to be the most effective heavy metal that causes the most significant decreases in biomass and chlorophyll a content. Our results showed that mercury applications caused to maximum decrease in SOD activity while APOD activity was decreased as a result of tin applications. Zinc, mercury and tin concentrations led to the significant reduction in GR activity as compared to control values. The treatments with increasing concentrations of zinc, tin and mercury progressively inhibited the growth of algae and chlorophyll-a valves during 7 days. The activity of SOD was mostly decreased by mercury, while the activity of SOD was by tin. The activity of GR were by both of the heavy metals. Keywords: Arthrospira platensis, chlorophyll-a, biomass, heavy metals, antioxidant enzymes.