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

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