哈维氏弧菌对泥蚶的毒性及半致死浓度研究

为构建泥蚶感染弧菌标准技术体系,本研究采用哈维氏弧菌浸泡感染和注射胁迫两种攻毒方式对泥蚶进行了急性毒性实验,观察泥蚶在菌液胁迫下的存活情况,分析哈维氏弧菌对泥蚶的半致死浓度。浸泡感染实验结果表明,随着感染水体中弧菌升高,泥蚶死亡起始时间和最大日死亡率时间均有所提前,泥蚶死亡情况呈现上升趋势,当浸泡浓度超过2×10⁷CFU/mL,泥蚶15 d累计死亡率接近100%。注射胁迫实验结果表明,泥蚶死亡率与弧菌注射浓度呈显著正相关(r=0.964,P<0.01)。Probit回归分析结果显示,哈维氏弧菌浸泡感染泥蚶7 d后停止实验,15 d的半致死浓度(LC₅₀)为1.35×10⁷CFU/mL;注射胁迫下的96 h半致死剂量(96 h LD₅₀)为2.12×10⁷CFU/g,说明哈维氏弧菌对泥蚶有明显的毒害作用。研究结果为泥蚶对哈维氏弧菌耐受性提供数据参考,并且为泥蚶弧菌病防治提供了理论基础。

Toxicity test and median lethal concentration of Vibrio harveyi for the blood clam Tegillarca granosa

This study aimed to establish a standard technical system to study the effect of Vibrio harveyi infection on the blood clam Tegillarca granosa. Acute toxicity testing was conducted by injecting and immersing T. granosa in different concentrations of V. harveyi. After the clam died due to the infection, the median lethal concentration (or dose) of V. harveyi was calculated. Results of the immersion infection experiment revealed that the time when clams began to die and when the maximum daily mortality occured become earlier as the concentration of V. harveyi increased. Initially, the mortality of clams increased rapidly, and the cumulative mortality rate of the clam was approximately 100% after 15 days, i.e., when the concentration of V. harveyi reached 2×10⁷ CFU/mL in the seawater. Results of the injection infection experiment showed that the mortality rate of clams was positively correlated with the injected concentration of V. harveyi (r = 0.964, P<0.01). The probit analysis showed median lethal concentration (LC₅₀) of the V. harveyi immersion infection was 1.35×10⁷ CFU/mL for 15 days (infection lasts for 7 days and statistics for 15 days). The 96-h lethal dose (96-h LD₅₀) of the V. harveyi injection was 2.12×10⁷ CFU/g. These results suggested that V. harveyi was toxic to T. granosa. Our results provided data regarding the tolerance of T. granosa to V. harveyi. This study also provided a theoretical basis for the prevention and treatment of vibriosis in T. granosa.