The Phaeobacter genus has been explored as probiotics in mariculture as a sustainable strategy for the prevention of bacterial infections. Its antagonistic effect against common fish pathogens is predominantly due to the production of the antibacterial compound tropodithietic acid (TDA), and TDA-producing strains have repeatedly been isolated from mariculture environments. Despite many in vitro trials targeting pathogens, little is known about its impact on host-associated microbiomes in mariculture. Hence, the purpose of this study was to investigate how the addition of a TDA-producing Phaeobacter inhibens strain affects the microbiomes of live feed organisms and fish larvae. We used 16S rRNA gene sequencing to characterize the bacterial diversity associated with live feed microalgae (Tetraselmis suecica), live feed copepod nauplii (Acartia tonsa), and turbot (Scophthalmus maximus) eggs/larvae. The microbial communities were unique to the three organisms investigated, and the addition of the probiotic bacterium had various effects on the diversity and richness of the microbiomes. The structure of the live feed microbiomes was significantly changed, while no effect was seen on the community structure associated with turbot larvae. The changes were seen primarily in particular taxa. The Rhodobacterales order was indigenous to all three microbiomes and decreased in relative abundance when P. inhibens was introduced in the copepod and turbot microbiomes, while it was unaffected in the microalgal microbiome. Altogether, the study demonstrates that the addition of P. inhibens in higher concentrations, as part of a probiotic regime, does not appear to cause major imbalances in the microbiome, but the effects were specific to closely related taxa.

中文翻译：

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用潜在的益生菌Phieobacter inhibens菌株处理后，海水养殖饲料微生物的微生物组的变化。

该Phaeobacter属已探索在海水养殖益生菌作为预防细菌感染的可持续发展战略。它对常见鱼类病原体的拮抗作用主要是由于产生了抗菌化合物对二硫代乙酸（TDA），并且已经从海水养殖环境中反复分离出了产生TDA的菌株。尽管有许多针对病原体的体外试验，但对于其对海水养殖中与宿主相关的微生物群的影响知之甚少。因此，本研究的目的是研究如何添加产生TDA的Phieobacter hihibens。菌株影响活饲料生物和鱼幼虫的微生物群落。我们使用16S rRNA基因测序来表征与活饲料微藻（Tetraselmis suecica），活饲料co足无节幼体（Acartiatonsa）和大菱turbo（Scophthalmus maximus）卵/幼虫相关的细菌多样性。微生物群落是所研究的三种生物所独有的，益生菌的添加对微生物群落的多样性和丰富性具有多种影响。活饲料微生物组的结构发生了显着变化，而与turbo类幼虫相关的群落结构未见影响。这些变化主要出现在特定的分类单元中。该Rhodobacterales这三个微生物群落都是固有的，当在in足类和菱形微生物群落中引入Inhibens P. inhibens时，其相对丰度降低，而在微藻微生物组中则不受影响。总之，该研究表明，作为益生菌方案的一部分，以较高的浓度添加P. inhibens似乎不会引起微生物组的重大失衡，但是这种作用是特定于密切相关的分类单元的。