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

有毒的短毛裸子鞭毛藻在墨西哥湾的大部分沿海水域都有大量繁殖，但佛罗里达海岸的问题尤其严重，这些年度事件持续至少3个月，给地区经济造成了巨大损失，估计每次损失约为2000万美元。目前的项目旨在开始阐明灭藻细菌在促进沿佛罗里达湾沿岸短曲赤潮的衰退和消散中的作用。在佛罗里达海湾沿岸的原生微生物组合中存在针对短杆菌的杀藻细菌的假设，使用了一种直接的、先前成功的方法进行了测试，该方法包括分离禁止或干扰短杆菌生长的细菌。分离介质用于选择需要短梭菌衍生有机物的细菌，这是几种先前描述的杀藻细菌的特征。还测试了一种支持菌株5n3生长的制剂，该菌株对短弧菌致命。分离的细菌具有特定的灭藻活性短弧菌用经典和分子技术进行了表征。后者将提供小亚单位（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。本文提出的工作代表了调查美国水域中杀藻细菌和有害藻华之间关系的第一次尝试。该项目预计将导致分离和鉴定一种细菌菌株，该菌株特异性抑制佛罗里达赤潮鞭毛藻G. breve的生长。ssu rRNA基因的测序和rRNA探针的后续开发将提供一种方法，通过这种方法可以跟踪这些细菌在受控（例如，中生态系统）以及自然系统中的种群，从而更好地评估它们在促进华度下降中的作用。最后，从这项研究中获得的知识是批判性评估杀藻细菌作为控制或调节有害藻华的手段的潜在用途的重要的第一步，这一过程目前正在其他受藻华严重影响的国家进行（例如，日本）。

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)