In the present study, a Gram-positive bacterium was isolated from the intestine of healthy crucian carp Carassius auratus and named strain R8. It was initially identified as Enterococcus faecium according to its morphological, physiological and biochemical characteristics. Further identification by using 16S rRNA gene sequence analysis confirmed the R8 strain (Genbank accession no. MF928076) as E. faecium. Challenge and hemolysis experiments showed that the E. faecium R8 strain had no toxicity to the crucian carp. Bacteriostatic experiment showed that this isolate obviously inhibited the growth of Aeromonas veronii and Staphylococcus haemolyticus. The proliferation of E. faecium R8 strain occurred after exposure to various growth conditions such as at pH values from 2.0 to 4.0 for 8 h, bile concentrations from 0.2 to 1.2% and high temperature of 80 °C. This bacterial strain grew best under the condition of 37 °C, pH 7.0 and salinity 30 ppt, and its growth curve exhibited four distinct phases. These results showed that the E. faecium R8 strain had potential probiotic characteristics and could be used as a candidate strain for aquatic probiotics.

中文翻译：

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来自the鱼Car鱼肠道的粪肠球菌益生菌候选菌株。

在本研究中，从健康cru鱼Car鱼的肠中分离出革兰氏阳性细菌，并将其命名为R8菌株。根据其形态，生理和生化特征，最初被鉴定为粪肠球菌。通过使用16S rRNA基因序列分析的进一步鉴定证实了R8菌株（Genbank登录号MF928076）为粪肠球菌。挑战和溶血实验表明，屎肠球菌R8菌株对the没有毒性。抑菌实验表明，该菌株明显抑制了维罗纳气单胞菌和溶血性葡萄球菌的生长。粪肠球菌R8菌株的增殖发生在暴露于各种生长条件下，例如在pH值从2.0至4.0持续8小时，胆汁浓度从0.2至1。2％和80°C的高温。该细菌菌株在37°C，pH 7.0和盐度30 ppt的条件下生长最佳，其生长曲线显示出四个不同的阶段。这些结果表明，粪肠球菌R8菌株具有潜在的益生菌特性，并且可以用作水生益生菌的候选菌株。