龙须菜对锥状斯氏藻抑制作用的机制

Inhibitory Effect of Gracilaria lemaneiformis(Bory) Weber Bosse on the Cocultured Scrippsiella trochoidea(Stein) Loeblich Ⅲ Under Controlled Laboratory Conditions

实验室条件下研究了共培养体系中龙须菜(Gracilaria lemaneiformis)对锥状斯氏藻(Scrippsiella trochoidea)生长的影响,并对其作用机制进行了初步探讨.结果显示,当龙须菜起始生物量为0.5 g.L-1时,在彼此隔离的共培养体系中,锥状斯氏藻的生长受到明显的抑制,与对照组相比,细胞最大密度降低并且对数生长期缩短;但这种抑制作用明显弱于在藻体直接接触的共培养体系中的抑制作用,说明藻体直接接触所产生的克生作用是导致龙须菜对锥状斯氏藻抑制作用的主要原因.当龙须菜起始生物量为0.2 g.L-1时,对隔离共培养体系中的锥状斯氏藻胞内营养盐含量的测定结果显示,单独培养组锥状斯氏藻胞内硝酸盐含量是共培养组的1.5倍,说明龙须菜能够通过竞争性吸收环境中的硝酸盐来降低锥状斯氏藻胞内硝酸盐的储存含量,从而有效抑制其生长.

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 at0.5g·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 strong 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 at0.2g·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.