Half‐smooth tongue sole Cynoglossus semilaevis is a high‐value marine fish species. The intensive farming of this flatfish species has been suffered from disease outbreak. Poly‐β‐hydroxybutyrate (PHB) is a carbon storage compound accumulated by a wide variety of prokaryotes and is considered biocontrol agent applied in aquaculture. In this study, the dietary effect of PHB‐accumulating Halomonas (HM.PHB) was investigated on survival, growth, resistance on Vibrio anguillarum and intestine microbial composition of C. semilaevis juveniles. Halomonas was fermented, which contained 76% PHB on cell dry weight. The fish juveniles were fed formulated feeds containing 1% HM.PHB, 3% HM.PHB and 5% HM.PHB, and 3% particle PHB (Par.PHB) and 3% Halomonas containing no PHB (HM) for 6 weeks. The basal feed feeding was considered as the control. The results revealed that both Halomonas‐PHB and particle PHB significantly improved the survival and growth of the juveniles than the control (p < .05), while HM was in between. When challenged with V. anguillarum, the survival rate in 1% HM.PHB, 3% HM.PHB and 5% HM.PHB was significantly improved than the control. Moreover, the increased intestine fold, epithelium height and surface were also observed in 3% HM.PHB. PCoA based on high‐throughput sequencing of 16S rRNA gene fragment indicated that dietary Halomonas‐PHB and particle PHB modified and stabilized the intestine microbial community of the fish. Our study demonstrated that Halomonas‐PHB is an effective feed additive for C. semilaevis juvenile culture. The outcome of this study facilitates the application of Halomonas‐PHB in C. semilaevis and other marine fish aquaculture.

中文翻译：

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Halomonas贮藏聚-β-羟基丁酸酯对半光滑舌半食蟹舌幼体存活，生长和抗纤维化的影响

半光滑的舌头半滑舌no（Cynoglossus semilaevis）是一种高价值的海洋鱼类。这种比目鱼的集约化养殖已遭受疾病爆发。聚-β-羟基丁酸酯（PHB）是多种原核生物积累的碳存储化合物，被认为是水产养殖中使用的生物防治剂。在这项研究中，PHB积累的膳食影响盐单胞菌（HM.PHB）进行了调查的存活，生长，电阻上鳗弧菌和肠微生物组合物的C.鳎幼鱼。盐单胞菌将其发酵，其中PHB占细胞干重的76％。向鱼类幼鱼喂食含有1％HM.PHB，3％HM.PHB和5％HM.PHB，3％颗粒PHB（Par.PHB）和3％不含PHB（HM）的Halomonas的配方饲料。将基础饲料喂养作为对照。结果显示，Halomonas- PHB和颗粒PHB均比对照组显着改善了幼虫的存活和生长（p  <.05），而HM介于两者之间。当受到V. anguillarum的挑战时，1％HM.PHB，3％HM.PHB和5％HM.PHB的存活率明显高于对照组。此外，在3％HM.PHB中也观察到肠折叠，上皮高度和表面增加。基于16S rRNA基因片段高通量测序的PCoA表明，日粮Halomonas ‐PHB和颗粒PHB修饰并稳定了鱼的肠道微生物群落。我们的研究表明Halomonas‐ PHB是半边念珠菌幼体培养的有效饲料添加剂。这项研究的结果有利于应用盐单胞菌-PHB在C.鳎等海水鱼类养殖。