海洋细菌Hahella sp. KA22对赤潮异弯藻的杀藻机制研究

海洋细菌在赤潮生消过程中起着重要作用，特别是杀藻菌，是赤潮生物防治中的最主要力量，其杀藻机制是研究的重要环节。在前期研究中，申请人从赤潮爆发原位环境分离到一株产杀藻色素的高效杀藻菌Hahella sp. KA22，该菌能够产生群体感应信号分子。虽然已有研究表明海洋细菌所产色素具有杀藻功能且其产生多与群体感应有关，但是关于色素杀藻机理及群体感应如何参与赤潮消亡的调控还有待深入研究。本项目基于前期研究基础，以赤潮异弯藻和杀藻菌KA22为研究对象，通过对杀藻色素结构、合成途径及作用方式研究，从分子水平揭示功能菌的杀藻机理；并基于群体感应基因分析、群体感应对杀藻色素及藻菌生物量影响的研究、结合中宇宙培养验证，探明群体感应对赤潮藻消亡的调控作用。结合分子水平及群体水平研究，最终阐释杀藻菌KA22对赤潮异弯藻的杀藻机制，从而深化对杀藻菌调控赤潮消亡机制的认识，为有效利用功能菌防治赤潮提供理论依据。

Marine bacteria play great roles in the process of harmful algal blooms (HABs), especially bacteria with anti-algal capability. Algicidal bacteria are important for controlling HABs, and the mechanism of algicidal functional bacterium toward HABs-causing algae has drawn more attentions recently. In our previous study, a novel algicidal bacterium Hahella sp. KA22 being capable of producing an algicidal pigment was isolated from marine environment, where HABs were detected. The algicidal bacterium also could produce quorum sensing signaling molecule. Although it was acknowledged that pigments produced by marine bacteria could kill HABs-causing microalgae and quorum sensing might involve into the production of these pigments, more works should be conducted to reveal the mechanism of killing microalgae by pigments and function of quorom sensing in the process of controlling HABs. In this proposal, the HABs-causing algae, Heterosigma akashiwo and the functional bacterium Hahella sp. KA22 are going to be used as model organisms to reveal these questions. By analyzing the construction of the algicidal pigment, its way and conditions of killing H. akashiwo and its synthetic pathway, the mechanism of its algicidal function is going to be detected. Further, combing verification experiments in mesocosm, quorom sensing signalling moleculars and their inhibitors are going to be used for demonstrating how quorom sensing control the bloom of H. akashiwo. Based on studies on molecular level and community leveal, we are trying to reveal the algicidal mechanism of functional bacterium Hahella sp. KA22 towards the HABs-causing microalgae H. akashiwo. This study will deepen our understanding and provide insights into mechanism of controlling HABs by functional bacterium.