In this study, 2 yeasts, Candida zeylanoides isolate Y12-3 (MN073455.1) and Hyphopichia pseudoburtonii isolate Y12-1 (MN073489.1), were isolated from rainbow trout hindguts. Their identity was confirmed by amplification of internal transcribed spacer (ITS) gene regions. Their in vitro probiotic properties showed that they were hydrophobic and did not inhibit bacterial growth. However, they displayed positive co-aggregation with several bacterial pathogens. It was interesting that Y12-1 and Y12-3 isolates survived and grew well in bile salt concentrations ranging from 0.6% to 1.5% and at low pH conditions. After a 35-day feeding trial, the results of dietary incorporation of the yeast isolates showed that serum myeloperoxidase activity was unchanged in the treated and control groups. Meanwhile, serum lysozyme activity in yeast groups was decreased significantly compared to the control. However, fish fed with Y12-1 had higher total protein, albumin, and globulin than other groups. Total cholesterol levels were decreased significantly in yeast groups compared to the control. Interestingly, the Y12-1 and Y12-3 groups showed higher survival (69.05% and 80.95%) after the challenge with Lactococcus garvieae compared to the control (45.24%). In brief, the aforementioned findings showed that Y12-1 and Y12-3 strains could be potential probiotic candidates for use in rainbow trout farming.

中文翻译：

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从虹鳟鱼 Oncorhynchus mykiss 的肠道中鉴定出具有潜在益生菌特性的新酵母菌株：Candida zeylanoides Y12-3 和 Hyphopichia pseudoburtonii Y12-1

在本研究中，从虹鳟鱼后肠中分离出2 种酵母菌，即Candida zeylanoides分离株 Y12-3 (MN073455.1) 和Hyphopichia pseudoburtonii分离株 Y12-1 (MN073489.1)。通过内转录间隔区（ITS）基因区域的扩增证实了它们的身份。它们的体外益生菌特性表明它们是疏水性的并且不会抑制细菌生长。然而，它们表现出与几种细菌病原体的正共聚集。有趣的是，Y12-1 和 Y12-3 分离株在胆盐浓度范围为 0.6% 至 1.5% 和低 pH 条件下存活并生长良好。经过 35 天的喂养试验，酵母分离物的饮食掺入结果表明，治疗组和对照组的血清髓过氧化物酶活性没有变化。同时，酵母组血清溶菌酶活性较对照组显着降低。然而，用 Y12-1 喂养的鱼比其他组的鱼具有更高的总蛋白、白蛋白和球蛋白。与对照组相比，酵母组的总胆固醇水平显着降低。有趣的是，与对照组（45.24％）相比，Y12-1和Y12-3组在用格氏乳球菌攻击后表现出更高的存活率（69.05％和80.95％）。简而言之，上述发现表明 Y12-1 和 Y12-3 菌株可能是用于虹鳟鱼养殖的潜在益生菌候选者。