Effects Of Inorganic Salts On Cysts Formation And Antioxidant Enzymes Activities Of Scrippsiella Trochoidea

Effects of inorganic nutrition factors (N, P and salinity) on the growth of the algae Scrippsiella trochoidea and its cysts formation and germination, as well as antioxidant enzymes activities were investigated in the present study.The growth of S. trochoidea was impacted under the conditions of deficiency of N and P, and the variation of salinity. The results of experiments demonstrated that P was a crucial element for the growth of S. trochoidea. In the P-free culture medium, algal growth curve can't be observed, and the maximum algal cells density was only 8700cells/mL, and entered into decline phase much earlier; Growth rate of algae at exponential phase was 0.2804time·d^-1 and the maximum cells density was 38600ceIIs/mL under the condition of deficiency of N, and had a decline of 25.37% and 37.64% compared with the control experiment, respectively; Growth of algae was limited by lower temperature, the growth rate at exponential phase is 0.3158 time·d^-1 and the maximum cells density is 24200cells/mL under 15℃, a decline of 15.9% and 60.9%, respectively; and elevating or reducing salinity impacted growth of algae, whose effect was less than the factors discussed above.Among the conditions of inducing cyst formation, the absence of P was the main factor. Cysts formed under single condition of P depletion or other multi-conditions; Under the single conditions of nitrogen depletion, declining the temperature or changing the salinity failed to induce cyst formation directly. Under the absence of P, the cyst formation ratio reached 21.29%, the maximum cysts density was 8700cells/mL and most of the formed cysts were temporary cysts, under appropriate conditions, the germination rate of the temporary cyst reached up to 91.54%. In addition, it was obversed that different cyst forms were shaped under different conditions.For S. trochoidea, the functions of SOD and CAT appeared in response to stresses. At the initial period of damage, the activities of SOD and CAT increased in order to protect cells, and then declined when the harm increased, and the more reactive oxygen species generated, and the algae suffered more damage.