地中海弧菌Vibrio mediterranei 117-T6的溶藻活性

很多藻类致病菌具有广谱溶藻活性。本研究发现紫菜黄斑病致病菌地中海弧菌Vibrio mediterranei 117-T6（Vm 117-T6）对赤潮异湾藻、颗石藻、叉编金藻和东海原甲藻等微藻也具有较强的溶藻活性，可使其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。Vm 117-T6能降解卡拉胶，不能降解果胶、纤维素和几丁质。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Toxin。这些研究结果提示Vm 117-T6毒力效应物中含有极性非蛋白质类物质，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。上述研究结果表明：多种溶藻机制参与了Vm 117-T6的溶藻过程。

Algicidal activity of Vibrio mediterranei 117-T6

Many algal pathogens have a broad spectrum of algae-lysing activity. In this study, Vibrio mediterranei 117-T6 (Vm 117-T6), a pathogenic bacterium for the yellow spot disease of Pyropia, showed a broad-spectrum algae-lysing activity. It exhibited strong lysing-algae activity to Heterosigma akashiwo (NMBjah045), Pleurochrysis carterae, Dirateria inornate and Prorocentrum donghaiense, which significantly reduces the chlorophyll content of these microalgaes. Vm 117-T6 can also reduce the motility of H. akashiwa 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 lysing-microalgae activity. The extracellular lysing-algae 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 polar non-proteinaceous substances, and the proteins related to the transport, secretion and cell adhesion may play an important role in the virulence of Vm 117-T6. Vm 117-T6 may achieve the goal of algae lysis by multiple mechanism.