Bacteria in nature are widely exposed to differential fluid shears which are often a trigger for phenotypic switches. The latter mediates transcriptional and translation remodelling of cellular metabolism impacting among others virulence, antimicrobial resistance and stress resistance. In this study, we evaluated the role of fluid shear on phenotypic switch in an acute hepatopancreatic necrosis disease (AHPND)‐causing Vibrio parahaemolyticus M0904 strain under both in vitro and in vivo conditions. The results showed that V. parahaemolyticus M0904 grown at lower shaking speed (110 rpm constant agitation, M0904/110), causing low fluid shear, develop cellular aggregates or floccules. These cells increased levan production (as verified by concanavalin binding) and developed differentially stained colonies on Congo red agar plates and resistance to antibiotics. In addition, the phenotypic switch causes a major shift in the protein secretome. At 120 rpm (M0904/120), PirA^VP/PirB^VP toxins are mainly produced, while at 110 rpm PirA^VP/PirB^VP toxins production is stopped and an alkaline phosphatase (ALP) PhoX becomes the dominant protein in the protein secretome. These observations are matched with a very strong reduction in virulence of M0904/110 towards two crustacean larvae, namely, Artemia and Macrobrachium. Taken together, our study provides substantial evidence for the existence of two phenotypic forms in AHPND V. parahaemolyticus strain displaying differential phenotypes. Moreover, as aerators and pumping devices are frequently used in shrimp aquaculture facilities, they can inflict fluid shear to the standing microbial agents. Hence, our study could provide a basis to understand the behaviour of AHPND‐causing V. parahaemolyticus in aquaculture settings and open the possibility to monitor and control AHPND by steering phenotypes.

中文翻译：

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环境条件引导急性肝胰腺坏死病的表型转换，引起副溶血性弧菌，影响PirAVP / PirBVP毒素的产生。

自然界中的细菌广泛暴露于不同的流体剪切，这通常是表型转换的触发因素。后者介导细胞代谢的转录和翻译重塑，其中影响了毒力，抗微生物性和抗逆性。在这项研究中，我们评估了在体外和体内条件下，液体剪切在急性肝胰腺坏死病（AHPND）致副溶血性弧菌M0904菌株中表型转换的作用。结果表明，副溶血性弧菌M0904在较低的摇动速度（110 rpm恒定搅拌，M0904 / 110）下生长，引起较低的流体剪切，形成细胞聚集体或絮凝物。这些细胞增加了levan的产量（通过刀豆球蛋白结合证实），并在刚果红琼脂平板上形成了不同染色的菌落，并对抗生素产生了抗性。此外，表型转换导致蛋白质分泌组发生重大变化。以120rpm（M0904 / 120），皮拉^VP / PirB的^VP毒素主要生产，而在110rpm的PIRA ^VP / PirB的^VP毒素生产停止，碱性磷酸酶（ALP）PhoX成为蛋白质分泌组中的主要蛋白质。这些观察结果与M0904 / 110对两个甲壳类幼虫，即Artemia和Macrobrachium的毒力非常强烈的降低相吻合。综上所述，我们的研究为显示不同表型的AHPND副溶血弧菌菌株中存在两种表型形式提供了实质性证据。此外，由于在虾类水产养殖设施中经常使用曝气器和泵送设备，因此它们可能对立式微生物产生剪切作用。因此，我们的研究可为理解引起副溶血性弧菌的AHPND行为提供基础。 在水产养殖环境中，并通过指导表型来监测和控制AHPND。