为验证地中海弧菌117-T6(Vm 117-T6)是否具有广谱溶藻性，本实验观察了其对赤潮异湾藻、颗石藻、叉鞭金藻和东海原甲藻的溶藻作用，并对其溶藻物质的特性进行了分析。结果表明，紫菜黄斑病致病菌Vm 117-T6对赤潮异湾藻、颗石藻、叉鞭金藻和东海原甲藻等微藻具有较强溶藻活性，可使藻类叶绿素含量显著降低，是一株广谱性溶藻细菌。Vm 117-T6能在40 min内使赤潮异弯藻的活动能力下降，光合作用受抑，感染120 min即可导致藻体裂解并产生白色絮状沉淀。该菌株能降解卡拉胶，不能降解果胶、纤维素和几丁质。Vm 117-T6菌体、胞内及胞外提取物均具有较强的溶藻活性，其胞外溶藻物质易溶于水、不溶于石油醚和乙酸乙酯，具较强极性；耐高温、不易被活性炭吸附、乙醇处理会降低溶藻活性。Vm 117-T6在常规与易感条件下的关键差异蛋白包括大量的ABC转运蛋白、外膜蛋白、鞭毛蛋白及少量毒素。上述结果提示，Vm 117-T6毒力效应物中含有极性的内毒素物质，且与毒力因子转运、分泌以及细胞黏附相关的蛋白可能在其毒力作用中发挥重要作用。本实验为解析该菌株溶藻机制提供了证据，为该菌的防治及应用提供了参考。

Many algal pathogens have a broad spectrum of algae-lysing activity. In order to verify whether Vibrio mediterranei 117-T6 (Vm 117-T6) has broad-spectrum algicide properties, this paper observed its algal lysis on Heterosigma akashiwo, Pleurochrysis carterae, Dirateria inornata and Prorocentrum donghaiense, and the characteristics of the algae-lysing substances were analyzed. In this study, Vm 117-T6, a pathogenic bacterium for the yellow spot disease of Pyropia, showed a broad-spectrum algae-lysing activity. It exhibited strong algae-lysing activity to H. akashiwo, P. carterae, D. inornata and P. donghaiense, which significantly reduces the chlorophyll content of these microalgaes. Vm 117-T6 can also reduce the motility of H. akashiwo within 40 min, inhibit photosynthesis, cause algal lysis and produce white flocculent precipitates after infection over the 120 min. Vm 117-T6 can degrade carrageenan, but cannot degrade pectin, cellulose and chitin. The live bacterium, its intracellular and extracellular extracts showed strong microalgae-lysing activity. The extracellular algae-lysing compounds were easily soluble in water, insoluble in petroleum ether and ethyl acetate, which indicated strong polarity. It was resistant to high temperature, and was not easy adsorbed by activated carbon. Ethanol treatment reduced the lysing-algae activity. There were a large amount of ABC transporter, outer membrane protein, flagellin and a small amount of toxin in the key differential proteins under conventional and susceptible conditions. The results indicate that Vm 117-T6 does not dissolve algae through cell wall degradation, and the virulence effectors of Vm 117-T6 contain endotoxins, and the proteins related to the transport, secretion and cell adhesion may play an important role in the virulence of Vm 117-T6. This paper provides evidence for the analysis of the algae-lysing mechanism of this strain, and also lays a foundation for the prevention and control of this strain.

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浙江省自然科学基金 (LY22C190002)；国家自然科学基金 (32273155)；宁波市科技创新重大专项 (2021Z004，2021Z104)；现代农业产业技术体系建设专项 (CARS-50)