龙须菜对3种赤潮微藻生长的影响

Effects of macroalga Gracilaria lemaneiformis on the growth of three species of red tide microalgae under laboratory conditions

在共生条件下,研究了鲜龙须菜对前沟藻、米氏凯伦藻和塔玛亚历山大藻等3种赤潮微藻生长的影响。在此基础上,以龙须菜培养水过滤液和龙须菜水溶性抽提液为实验用液,分析它们对上述3种赤潮微藻的抑制作用。最后,采用甲醇浸泡龙须菜干粉末,研究了其甲醇提取物对3种赤潮微藻生长的影响。结果表明,当鲜龙须菜浓度≥32 g.L-1时,其能显著抑制3种赤潮微藻的生长,对它们的生长抑制率在42%以上。在龙须菜（浓度为32 g.L-1）培养水过滤液的实验中,发现无论一次性还是在半连续添加方式,培养水过滤液都对3种赤潮微藻表现出较为明显的抑制作用;同时发现,40~80℃下处理此培养水过滤液,其抑藻作用并未显著减弱,可见龙须菜抑藻物质有较高的热稳定性。当龙须菜水溶性抽提液浓度为16 g.L-1时,其显著了抑制3种赤潮微藻的生长。龙须菜干粉末的甲醇提取物同样能显著抑制3种赤潮微藻的生长,在甲醇提取物浓度为2.0 g.L-1时,对3种赤潮微藻的生长抑制率超过40%。上述结果表明,抑藻物质不仅存在于鲜龙须菜中,还存在于其干粉末中。

To study the effects of fresh Gracilaria lemaneiformis on the growth of the three species of red tide microalgae（Amphidinium hoefleri,Karenia mikimitoi and Alexandrium tamarense）,those microalgae coexist with different initial inoculation concentrations of fresh tissue of G.lemaneiformis,respectively.Furthermore,the inhibitory activities against three species of red tide microalgae of fresh G.lemaneiformis＇s culture filtrate and aqueous extracts of G.lemaneiformis were tested.The extracts were extracted from the dry powder of G.lemaneiformis with methanol,and to probe their inhibitory effects on the growth of those microalgae.The results showed that the fresh tissue of G.lemaneiformis had strong growth inhibitory effect on A.hoefleri,K.mikimitoi and A.tamarense at the concentration of 32 g·L-1 and the growth inhibitory for three species of red tide microalgae was above 42%.The culture medium filtrate of G.lemaneiformis（the concentration of 32 g·L-1） could significantly inhibit the growth of the three species of the red tide microalgae under initial or semi-continuous filtrate addition.The further investigation found that the culture medium filtrate of G.lemaneiformis that had gentle heat for 60 minutes under different lengths of temperature（40℃,60℃ and 80℃） also had significant inhibitory effect on the growth of all test microalgae;this suggested that the inhibitory substances had higher thermal stability.The growth of all test microalgae was restrained by fresh G.lemaneiformis＇s aqueous extracts when concentration was 16 g·L-1.The methanol extracts of G.lemaneiformis dry powder also inhibited significantly those three species of red tide microalgae at the concentration of 2.0 g·L-1,and the growth inhibitory for three species of red tide microalgae was above 40%.It indicated fresh G.lemaneiformis had the inhibitory substances and inhibitory substances exited also in G.lemaneiformis＇s dry powder.