Identification and characterization of potentially algal-lytic marine bacteria strongly associated with the toxic dinoflagellate Alexandrium catenella
Identification and characterization of potentially algal-lytic marine bacteria strongly associated with the toxic dinoflagellate Alexandrium catenella
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DOI：
10.1111/j.1550-7408.2005.00031.x
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发表时间：
2005-05-01
影响因子：
2.2
通讯作者：
Suárez-Isla, BA
中科院分区：
文献类型：
--
作者：
Amaro, AM;Fuentes, MS;Suárez-Isla, BA
从智利南部峡湾分离出的有毒甲藻链状亚历山大藻产生几种石房蛤毒素类似物，并与麻痹性贝类中毒的爆发有关。三个细菌菌株，这仍然是在培养中与这种甲藻密切相关，分离到的甲藻在海洋琼脂。纯化表型不同的可培养细菌菌落。通过聚合酶链反应扩增16S rRNA基因进行遗传鉴定。部分序列分析表明，最可能的隶属关系是两个细菌门：变形菌和噬纤维菌组。分子鉴定由形态学数据和生化分析补充。这三种细菌在高营养培养基中与浮游植物细胞分开生长时，释放出溶藻化合物以及氨肽酶、脂肪酶、氨基葡萄糖苷酶和碱性磷酸酶。当相同的细菌，不含有机营养物，被添加回藻类培养物，他们没有表现出对甲藻细胞的有害影响，并恢复其共生特性。这一观察结果与系统发育分析相一致，系统发育分析揭示这些细菌对应于与先前分类为溶藻细菌的其他细菌菌株不同的物种。因此，细菌衍生的裂解活性仅在高营养培养基存在下表达，并且很可能原位环境条件可以调节其表达。
The toxic dinoflagellate Alexandrium catenella isolated from fjords in Southern Chile produces several analogues of saxitoxin and has been associated with outbreaks of paralytic shellfish poisoning. Three bacterial strains, which remained in close association with this dinoflagellate in culture, were isolated by inoculating the dinoflagellate onto marine agar. The phenotypically different cultivable bacterial colonies were purified. Their genetic identification was done by polymerase chain reaction amplification of the 16S rRNA genes. Partial sequence analysis suggested that the most probable affiliations were to two bacterial phyla: Proteobacteria and the Cytophaga group. The molecular identification was complemented by morphological data and biochemical profiling. The three bacterial species, when grown separately from phytoplankton cells in high-nutrient media, released algal-lytic compounds together with aminopeptidase, lipase, glucosaminidase, and alkaline phosphatase. When the same bacteria, free of organic nutrients, were added back to the algal culture they displayed no detrimental effects on the dinoflagellate cells and recovered their symbiotic characteristics. This observation is consistent with phylogenetic analysis that reveals that these bacteria correspond to species distinct from other bacterial strains previously classified as algicidal bacteria. Thus, bacterial-derived lytic activities are expressed only in the presence of high-nutrient culture media and it is likely that in situ environmental conditions may modulate their expression.