Vibrio disease is a prevalent bacterial infection in aquaculture, and using bacteria with antagonistic properties against Vibrio species as probiotics has emerged as a promising method for disease prevention. Additionally, low biomass productivity of microalgae feed remains a significant bottleneck in bivalve aquaculture. Therefore, it is essential to screen for bacteria that both enhance microalgae growth and inhibit Vibrio pathogens. In this study, seven bacterial strains capable of promoting microalgae growth were screened for their ability to inhibit three Vibrio pathogens, i.e., Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio cholerae, and thus serve as a dual-functional probiotic for aquaculture. The antagonistic mechanism of these bacteria was further investigated by analyzing the inhibitory effects of their extracellular products (ECP) on Vibrio species. Results indicated that Pseudoalteromonas flavipulchra exhibited antagonistic effects against all three Vibrio species tested. The ECP of P. flavipulchra displayed stable antibacterial activity, though this ability was lost after the ECP was treated with heat, alkali, or proteinase K. The proteinaceous fraction isolated from the ECP by precipitation with 90% saturated ammonium sulfate demonstrated concentration-dependent antibacterial activity. These findings suggest that P. flavipulchra could serve as a promising dual-functional probiotic for aquaculture, warranting further research to optimize its application in this field.

中文翻译：

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Pseudoalteromonas flavipulchra 作为水产养殖的双功能益生菌：增强微藻生长和拮抗弧菌病原体


弧菌病是水产养殖中一种普遍的细菌感染，使用对弧菌物种具有拮抗特性的细菌作为益生菌已成为一种很有前途的疾病预防方法。此外，微藻饲料的低生物量生产力仍然是双壳类水产养殖的重要瓶颈。因此，必须筛选既能促进微藻生长又能抑制弧菌病原体的细菌。在这项研究中，筛选了 7 种能够促进微藻生长的细菌菌株，它们能够抑制 3 种弧菌病原体，即创伤弧菌、副溶血性弧菌和霍乱弧菌，从而作为水产养殖的双重功能益生菌。通过分析这些细菌的细胞外产物 （ECP） 对弧菌属的抑制作用，进一步研究了这些细菌的拮抗机制。结果表明，Pseudoalteromonas flavipulchra 对所有三种测试的弧菌物种均表现出拮抗作用。P. flavipulchra 的 ECP 显示出稳定的抗菌活性，尽管这种能力在用热、碱或蛋白酶 K 处理 ECP 后丧失。通过用 90% 饱和硫酸铵沉淀从 ECP 中分离的蛋白质组分显示出浓度依赖性的抗菌活性。这些发现表明 P. flavipulchra 可以作为一种很有前途的水产养殖双功能益生菌，值得进一步研究以优化其在该领域的应用。