以一株黄斑病致病菌Vibrio mediterranei 117-T6感染坛紫菜的自由丝状体，研究了环境因子对该菌株生长的影响及其最易感条件，检测了该条件下V. mediterranei 117-T6引发的坛紫菜丝状体的抗氧化酶(SOD、POD)活性以及藻胆蛋白、叶绿素a(Chl. a)、可溶性蛋白、游离脯氨酸(Pro)和丙二醛(MDA)含量等生理指标的变化。结果显示，V. mediterranei 117-T6的最优生长条件为30 ℃、pH 7.0、盐度20，最易感条件为30 ℃、pH 6.0、盐度20。在易感条件下培养12 h后，感染组坛紫菜丝状体的SOD和POD的活性，藻胆蛋白、可溶性蛋白以及游离Pro含量等指标均显著高于对照组；MDA含量峰值出现在6 h，显著高于对照组；在24 h后，感染组的Chl. a含量达到峰值，亦显著高于对照组。研究表明，短期内弧菌感染虽然可以刺激坛紫菜丝状体产生胁迫应激反应，但是随着感染时间的延长，致病菌感染引发的藻体内活性氧及渗透压胁迫加剧，最终导致紫菜死亡。高温和酸化等不良的环境会加剧V. mediterranei 117-T6引发的坛紫菜黄斑病的恶化，其作用程度依次为温度、pH和盐度。

Pyropia species were the most popular algae cultivated in China with great commercial importance. Yellow spot disease (YSD) was a high-incidence infectious disease in the conchocelis filament sporing stage of Pyropia, which seriously affects the production. In this paper, the free living conchocelis filament of Pyropia haitanensis were infected by Vibrio mediterranei 117-T6, a YSD pathogen. The effects of environmental factors on the growth of the strain and its infectious ability were studied. The activities of SOD, POD and the contents of phycobiliprotein, chlorophyll a (Chl. a), soluble protein, free proline (Pro) and malondialdehyde (MDA) in the algae were measured under susceptible infectious conditions. The results showed that the optimum growth conditions of V. mediterranei 117-T6 were 30 ℃, pH 7.0 and salinity 20, while the most susceptible infectious conditions were temperature 30 ℃, pH 6.0 and salinity 20. After it was infected by V. mediterranei 117-T6 under the susceptible infectious conditions for 12 hours, the activity of SOD, POD, the content of phycobiliprotein, soluble protein and free proline in P. haitanensis conchocelis filaments were significantly higher than those in the control group (P<0.05). The content of MDA reached the highest value at 6 hours and was significantly higher than that in the control (P<0.05). After being infected for 24 hours, the content of Chl a in the infectious group achieved the highest, which was significantly higher than that in the control group (P<0.05). The study showed that in a short period, V. mediterranei 117-T6 could stimulate the algae to produce stress-response reactions. However, with the estension of the infection, the reactive oxygen species and osmotic pressure in the algae caused by pathogen increased and finally could lead to the death of Pyropia. Adverse environmental factors such as high temperature and acidification can exacerbate the infectious ability of V. mediterranei 117-T6, and the secondary factors were temperature, pH and salinity. The results suggested that the comprehensive treatment of Pyropia YSD should be carried out from the two aspects: the environment and the pathogenic bacteria.

S946.2

国家自然科学基金(31772871)；浙江省重大科技专项(2016C02055-6B)；藻类产业技术体系(CARS-50)