Abstract: In this study, Streptococcus salivarius subsp. thermophilus BD9818, isolated from koumiss, was evaluated for its safety via hemolytic activity assay and animal pathogenicity test, and the sleep-improving effect of its postbiotic was investigated using a zebrafish model of insomnia. The results demonstrated that strain BD9818 was non-hemolytic and exhibited no pathogenicity in animals, thus confirming its safety for application. Furthermore, low (250 μg/mL), medium (500 μg/mL), and high (1 000 μg/mL) doses of the postbiotic BD9818 all significantly reduced the awakening activity (P < 0.01, P < 0.01, and P < 0.001) and total awakening time (P < 0.05, P < 0.01, and P < 0.001) of zebrafish, while significantly up-regulating the expression level of the gabra1 gene (P < 0.05 for the low and medium doses, P < 0.01 for the high dose group). In conclusion, strain BD9818 is safe for consumption, and its postbiotic possesses favorable sleep-improving activity.

Key words: Streptococcus salivarius subsp. thermophilus BD9818; postbiotics; safety evaluation; pathogenicity; sleep improvement

摘要： 以分离自酸马乳的唾液链球菌嗜热亚种（Streptococcus salivarius subsp. thermophilus）BD9818为研究对象，通过溶血性检测与动物致病性试验评价该菌株的食用安全性，同时利用斑马鱼失眠模型探究其后生元的睡眠改善效果。结果表明，菌株BD9818为溶血性阴性菌株，且无动物致病性，具有良好的食用安全性；低（250?μg/mL）、中（500?μg/mL）、高剂量（1?000?μg/mL）BD9818后生元均可显著减少斑马鱼的觉醒活动量（P＜0.01，P＜0.01，P＜0.001）、缩短觉醒总时间（P＜0.05，P＜0.01，P＜0.001），并显著上调gabra1基因表达水平（低、中剂量组P＜0.05，高剂量组P＜0.01）。综上，唾液链球菌嗜热亚种BD9818具有食用安全性，且其后生元具备良好的睡眠改善作用。

关键词: 唾液链球菌嗜热亚种BD9818；后生元；安全性评价；致病性；改善睡眠