ECOHAB: Algicidal Bacteria and the Regulation of Gymnodiniumbreve Blooms in the Gulf of Mexico

有毒的短裸甲藻水华发生在墨西哥湾大部分沿海水域，但佛罗里达州海岸的问题尤其严重，那里的年度事件持续至少3个月，给该地区经济造成巨大损失，估计每起事件造成约2000万美元的损失。目前的项目旨在开始阐明杀藻细菌在促进佛罗里达州墨西哥湾沿岸短赤潮的消退中所起的作用。使用一种以前成功的简单方法来测试这一假设，即特定于G.breve的藻类细菌存在于佛罗里达州墨西哥湾沿岸本地的微生物组合中，该方法涉及分离禁止或干扰G.breve生长的细菌。分离介质用于需要G.breve衍生有机物的细菌，这是之前描述的几种杀藻细菌的特征。还测试了一种支持细菌5N3生长的配方，5N3是一种对短杆菌致死的菌株。利用经典技术和分子生物学技术对短小革兰氏菌具有杀藻活性的细菌进行了鉴定。后者将提供小亚基(SSU)rRNA序列数据，这些数据将在后续研究中用于设计和开发这些细菌菌株的寡核苷酸探针。本文提出的这项工作是首次尝试调查美国水域中杀藻细菌与赤潮之间的联系。该项目预计将导致分离和鉴定一种细菌菌株(S)，该菌株专门抑制佛罗里达州赤潮甲藻G.breve的生长。SSU rRNA基因的测序和随后rRNA探针的开发将提供一种手段，用于跟踪这些细菌在受控系统(例如，中游系统)以及自然系统中的种群，从而更好地评估它们在促进水华衰退方面的参与。最后，从这项研究中获得的知识是批判性地评估使用杀藻细菌作为控制或控制赤潮的手段的可能性的关键的第一步，这一过程目前正在受到赤潮严重影响的其他国家(例如日本)进行。

Blooms of the toxic dinoflagellate Gymnodinium breve occur in coastal waters throughout much of the Gulf of Mexico, but are especially problematic along the Florida coast where these annual events last at least 3 months and exact a large toll on the regional economy with losses estimated at about $20 million per episode. The current project is aimed at beginning to elucidate the role of algicidal bacteria in promoting the decline and dissipation of G. breve red tides along the Florida Gulf coast. The hypothesis that algicidal bacteria specific for G. breve are present in microbial assemblages indigenous to the Florida Gulf coast is tested using a straightforward, previously successful, approach which involves isolating bacteria that prohibit or interfere with the growth of G. breve. Isolation media used select for bacteria requiring G. breve derived organics, a characteristic of several previously described algicidal bacteria. A formulation supporting growth of bacterial strain 5N 3, a strain lethal to G. breve is also tested. Bacterial isolates with algicidal activity specific for G. breve are characterized with classical and molecular techniques. The latter will provide small subunit (ssu) rRNA sequence data, which will be used during a follow up study to design and develop oligonucleotide probes for these bacterial strains. The work proposed herein represents the first attempt to investigate the association between algicidal bacteria and HABs in U.S. waters. This project is anticipated to result in the isolation and identification of a bacterial strain(s) which inhibits specifically the growth of the Florida red tide dinoflagellate, G. breve. Sequencing of the ssu rRNA gene and the subsequent development of rRNA probes will provide a means by which to track populations of these bacteria in controlled (e.g., mesocosms) as well as natural systems, and thus to better assess their involvement in promoting bloom decline. Finally, the knowledge gained from this study is an essential first step in critically evaluating the potential use of algicidal bacteria as a means of controlling or regulating HABs, a process currently underway in other countries severely impacted by algal blooms (e.g., Japan)