一株中肋骨条藻特异溶藻菌的分离鉴定及溶藻特性

Isolation and algicidal characteristics of a specific algicidal bacterium on Skeletonema costatum

摘要:

【背景】赤潮频发引起严重的海洋生态学问题，不仅直接影响到海洋生态系统稳定、海洋生物资源可持续利用和水产养殖业等海洋产业的健康发展，而且对人类健康也构成了严重威胁。高效的溶藻细菌是生物法防控赤潮的有效工具之一。【目的】分离得到对中肋骨条藻具有高效溶藻效果的溶藻细菌，并对其进行分子鉴定，研究该菌株的溶藻机理以及溶藻菌所分泌溶藻物质的特性。【方法】采用2216E平板稀释涂布法分离纯化细菌，测定16S rRNA基因序列以鉴定细菌种类，利用显微镜计数溶藻菌处理后的目标藻种计算溶藻率，通过扫描电镜观察溶藻菌对中肋骨条藻的溶藻过程，利用常规生理生化方法研究溶藻菌溶藻物质的特征，并通过透析袋截留法研究溶藻物质分子量大小。【结果】分离得到一株中肋骨条藻高效溶藻菌FDHY-CJ，该菌株属于交替单胞菌属(Alteromonas sp. FDHY-CJ)。该菌株72 h处理赤潮藻结果显示，对中肋骨条藻溶藻率为95.45%，对于其他常见赤潮藻溶藻率低于40%。溶藻菌FDHY-CJ通过胞外分泌物溶藻；溶藻物质的溶藻特性不受反复冻融的影响，但对酸碱性及温度较为敏感；扫描电镜观察结果显示该溶藻菌的溶藻物质直接溶解中肋骨条藻的细胞壁，致使硅质壳打开、内容物流出，达到溶藻的效果；溶藻活性物质具有被乙醇和乙酸乙酯沉淀的特性。【结论】溶藻菌FDHY-CJ对中肋骨条藻具有特异溶藻作用，对其他常见赤潮溶藻效果不明显；该细菌溶藻方式为通过分泌物间接溶藻，溶藻物质属于蛋白类，大小在3.5?10.0 kD之间。

Abstract:

[Background] The frequent occurrence of harmful algae blooms causes serious marine ecological problems, which not only directly affects the stability of marine ecosystems, the sustainable use of marine biological resources, and the healthy development of marine aquaculture, but also lead to a serious threat to human health and even life. Efficient algae-lysing bacteria are one of the effective tools to control harmful algae blooms by biological methods. [Objective] Isolation and molecular identification of algae-lysing bacteria with high algicidal effect on Skeletonema costatum, and studying the algae-lysing mechanism of this strain and the characteristics of algae-lysing substances secreted by algae-lysing bacteria. [Methods] The 2216E plate dilution method was used to isolate and purify bacteria. The 16S rRNA gene sequence was determined to identify the bacterial species. The cell concentration was monitored using microscope for both control and treatment to calculate algicidal rate. The algicidal progress of challenged S. costatum was observed by scanning electron microscope. The algae-dissolving process of S. costatum was studied by using conventional physiological and biochemical methods to study the characteristics of algae-lysing substances. The molecular weight of algae-lysing substances was detected by dialysis bag retention method. [Results] A high-efficiency alginolytic bacterium FDHY-CJ for S. costatum was isolated, which belonged to the genus Alteromonas (Alteromonas sp. FDHY-CJ). The 72-hour treatment of red tide algae by this strain showed that the algae lysis rate was 95.45% against S. costatum and less than 40% for other common red tide algae. Algae-lysing FDHY-CJ lyses algae through extracellular secretions. The algae-lysing properties of algae-lysing substances are not affected by repeated freezing and thawing, but are sensitive to acidity, alkalinity and temperature. Scanning electron microscopy observations showed that the algae-lysing bacteria’s algae the substance directly dissolves the cell wall of S. costatum, causing the siliceous shell to open and the contents to flow out, then the algae was lysed. The algae-lysing active substance has the characteristics of being precipitated by ethanol and ethyl acetate. [Conclusion] The algae-lysing bacteria FDHY-CJ has specific algae-lysing effect on S. costatum. The bacterial algae-lysing was indirect algae-dissolving through secretion, and the molecular weight of this compound was between 3.5 kD and 10.0 kD.