Abstract:In this study we performed a series of experiments in order to find an effective control of dinoflagellate in microalgal community of the water environment. Scrippsiella trochoidea, Cyclotella striata, Chlorella pyrenoidosa, and Scenedesmus quadricauda were used as representative microalgal species in this study. Strain A3 was added into either monoculture or mix-culture systems of the four microalgaes at a concentration of 107 CFU/ml, and the morphology and cell density of the microalgae were analyzed every 48 hours for 10 days. Treated with A3, S. trochoidea in the monoculture system lost the motion activity on Day 1, then they inflated and finally lysed on Day 5. The cell density of S. trochoidea was 7.07×102 cells/ml on Day 10, which was significantly lower than that of the control group (P<0.05). Morphology of C. pyrenoidosa was not affected by Strain A3. The cell density of C. pyrenoidosa was 2.58×107 cells/ml on Day 10, and it was higher than that of the control group (P<0.05). Morphology of S. quadricauda was also unaffected by Strain A3. There was no significant difference in the cell density of S. quadricauda between the experimental group and the control group (P>0.05). C. striata lysed due to the effects of A3 on Day 8, and the cell density of C. striata in the control group and the experimental group were 4.38×105 cells/ml and 1.78×105 cells/ml, respectively. The lytic effect of Strain A3 on four microalgal species in the mix-culture systems was similar to that in the monoculture systems. These results suggested that Strain A3 might have strong lytic effect on S. trochoidea in the mix-culture systems. However, Strain A3 did not inhibit the growth of S. quadricauda and C. pyrenoidosa, and had weaker lytic effect on C. striata. Therefore, the algicidal activity of Strain A3 was highly specific to S. trochoidea, and hence could be used to develop probiotics against dinoflagellate blooms in aquaculture ponds.
