Abstract

γ-aminobutyric acid (GABA) is crucial in neural inhibition and sleep regulation. This study screened lactic acid bacteria isolated from breast milk and infant fecal samples for their GABA-producing ability; their acid tolerance, bile salt resistance, and growth performance were evaluated. Based on TLC-HPLC analysis, Lactobacillus gasseri F002, Lactiplantibacillus plantarum R7, and Lacticaseibacillus rhamnosus B2-1 were identified as promising GABA-producing strains. L. gasseri F002 was selected for liquid-state fermentation of the Baihe Dihuang decoction. During fermentation, L. gasseri F002 utilized carbohydrates in the decoction matrix, increased GABA accumulation, with a peak of 0.063 mg/mL at 24 h, and reduced total saponin content, suggesting that lactic acid bacterial fermentation induced compositional shifts of major functional constituents in the Baihe Dihuang decoction. The sleep-promoting effect of the fermented decoction was assessed using a caffeine-induced zebrafish insomnia model. The fermented Baihe Dihuang decoction significantly prolonged sleep bout duration, while reducing wakefulness and total locomotor activity. Moreover, correlative changes altered sleep-related molecular and biochemical indicators in the zebrafish model. Correlative changes in the expression of gabra1, htr1aa, drd2a, dbh, and th, as well as in GABA, melatonin (MT), and monoamine oxidase (MAO) levels, suggest a potential association with the observed sleep-improving phenotypes. Therefore, fermentation with GABA-producing lactic acid bacteria may enhance the sleep-promoting potential of the Baihe Dihuang decoction and provide preliminary experimental support for the development of fermented medicinal–food homologous products aimed at improving sleep.

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