Inhibitory effect of Gracilaria lemaneformis (Bory) Weber Bosse on the co-cultured Scrippsiella trochoidea (Stein) Loeblich III under controlled laboratory conditions
龙须菜对锥状斯氏藻抑制作用的机制

Abstract: The inhibitory effects of Gracilaria lemaneiformis on the co-cultured Scrippsiella trochoidea were determined under controlled laboratory conditions, and the possible mechanism was studied. Results showed that : (1) In the separating S. trochoiea- G. lemaneiformis co-culture system when the initial cell density of G. lemaneiformis was set at 0.5 g?L-1, the growth of S. trochoidea was obviously inhibited and its maximum cell density and exponential phase were decreased compared with the control; however, the inhibitory effect was not as stronger as that in the direct cell-cell contact co-culture. Result showed that allelopathy basing on the direct cell contact was the most possible reason leading to the observed result; (2) When the initial cell density of G. lemaneiformis was set at 0.2 g?L-1 in the direct cell-cell contact co-culture, the intracellular nitrate concentration of S. trochoidea in monoculture system was 1.5 times of that in co-culture. It seemed that G. lemaneiformis could competitively absorb the environmental nitrate and ultimately led to the decrease of the stock of intracellular nitrate of S. trochoidea.