实验海洋生物学重点实验室知识库

        急性肝胰腺坏死病是由致病性弧菌引起的对虾病害，对全球对虾养殖业造 成了重大经济损失。本文从排污海水环境中取样，筛选和鉴定出对致急性肝胰 腺 坏 死 病 副 溶 血 性 弧 菌 （Vp_AHPND）具有抑制作用的一株拮抗菌 Pseudoalteromonas sp. 1125（以下简称为 Ps1125），并初步探究其抑菌机制和对 对虾急性肝胰腺坏死病的防治效果。

        从山东省东营市的对虾工厂化养殖排污海水中取样，采用平板对峙法初筛 得到能抑制副溶血弧菌的拮抗菌株，采用打孔法复筛选出抑菌圈最大的目的菌 株。经过 16SrDNA、gyrB、ropD 基因序列比对和产酶能力测试，初步认为该菌 株属于假交替单胞菌属（Pseudoalteromonas）细菌，能产生脂肪酶、蛋白酶和 淀粉酶。 通过对 Ps1125 的抑菌机制进行探究，结果表明其抑菌作用需要细胞间的直 接接触，而与无细胞上清液和胞内产物无关。安全性实验结果表明，该菌株对 仔虾、成虾均不具有毒害作用，未观察到细胞溶血现象。Ps1125 加入养殖水体， 在初期具有降低水体中和对虾肝胰腺内的弧菌数量的效果，在攻毒之后的初期 阶段观察到对虾肝胰腺弧菌数量显著降低，且显著提高了副溶血弧菌攻毒后凡 纳滨对虾的存活率。无论是弧菌攻毒前 24h 添加 Ps1125 还是 Ps1125 与弧菌同时添加，均能有效降低水体内副溶血弧菌数量，提高凡纳滨对虾存活率，而对虾 感染弧菌后再添加该菌株，未提高对虾存活率。

        本研究筛选出了一株海洋细菌，体外实验表明其具有良好的抗弧菌和产酶 能力，可通过菌体细胞直接接触的方式对副溶血弧菌产生抑制作用。水体添加 和攻毒实验结果表明，其在一定程度上可降低水体和虾体内弧菌数、提高对虾存活率。菌株 Ps1125 在对虾养殖中具有潜在应用价值，为凡纳滨对虾急性肝胰 腺坏死病的生物防控提供了新的思路。

    Acute hepatopancreatic necrosis is a shrimp disease caused by pathogenic Vibrio spp., which has caused significant economic losses to the global shrimp farming industry. This article screened and identified an antagonistic bacterium Pseudoalteromonas sp. strain 1125 (hereinafter referred to as Ps1125) from the marine aquaculture effluent, which has an inhibitory effect on Vibrio parahaemolyticus (Vp_AHPND) causing acute hepatopancreatic necrosis. The antibacterial mechanism and preventive effect on acute hepatopancreatic necrosis in shrimp were preliminarily explored. Samples were taken from seawater of shrimp factory after aquaculture in Dongying, Shandong province, and antagonistic strains that can inhibit V. parahaemolyticus were initially screened using the agar disk diffusion method. The target strain with the largest inhibition zone was selected through re-screening using the drilling method. After 16SrDNA, gyrB, and ropD gene sequence alignment and enzyme production ability test, it is preliminarily believed that the strain belongs to the Pseudoalteromonas genus and can produce lipase, protease, and amylase. Through exploring the antibacterial mechanism of Ps1125, the results showed that its antibacterial effect requires direct contact between cells, and is independent of supernatant and intracellular products. The safety experiment results showed that the Ps1125 strain did not have toxic effects on both larva and adult shrimp, and no cell hemolysis was observed. The addition of Ps1125 to aquatic body has the effect of reducing the number of Vibrio spp. in the water as well as shrimp hepatopancreas in the initial stage. In the early stage after challenge, a significant decrease in the number of Vibrio spp. in the hepatopancreas was observed, significantly improving the survival rate of Litopenaeus vannamei after being infected with Vp_AHPND. Both the addition of Ps1125 24 hours before Vp_AHPND infection and the simultaneous addition of Ps1125 and Vp_AHPND can effectively reduce the number of Vibrio spp. in the water and improve the survival rate of the shrimp. However, adding this strain to shrimp infected with VpAHPND did not improve the survival rate of shrimp. This study identified a strain of marine bacteria, and in vitro experiments showed that it has good resistance to Vp_AHPND and enzyme production ability. It may exert inhibitory effects on V. parahaemolyticus through direct contact with bacterial cells. Directly adding Ps125 to water or challenged shrimp by Vibrio can, to a certain extent, reduce the number of Vibrio bacteria in the water and shrimp and improve the survival of shrimp. The results of water addition and Vibrio challenge indicate that it can to some extent reduce the number of V. parahaemolyticus in water and shrimp, and improve the survival rate of shrimp. The strain Ps1125 has potential application value in shrimp aquaculture, providing new ideas for the biological prevention and control of Vp_AHPND in L. vannamei.