Abstract: [Objective] To isolate and screen lactic acid bacteria capable of degrading condensed tannins from Onobrychis viciifolia （sainfoin） and to optimize their degradation conditions. [Methods] Naturally fermented Onobrychis viciifolia samples,collected from experimental fields in the grassland and animal husbandry park of the Horinger County,Inner Mongolia, were used to isolate and screen lactic acid bacteria that met the specified criteria. Initial screening was conducted using bacterial culture media,followed by secondary screening based on tannin degradation rates to select strains with superior degradation capabilities for condensed tannins from Onobrychis viciifolia. The selected strain was identified using 16S rDNA sequence analysis. Furthermore,the effects of varying inoculum amounts,culture time,and culture temperature on the degradation rate of condensed tannins from Onobrychis viciifolia were investigated to determine the optimal degradation conditions. [Results] Following fermentation of Onobrychis viciifolia,33 strains of lactic acid bacteria meeting the criteria were isolated. After initial and secondary screening, one strain YHD2-6,exhibited strong condensed tannin degradation ability and was identified as Lactobacillus plantarum. The optimal culture conditions for YHD2-6 were determined to be an inoculum amount of 10%,a culture time of 96 h,and a culture temperature of 37 ℃,under which the degradation rate of condensed tannins reached 76.73%. [Conclusion] This study successfully screened a strain of Lactobacillus plantarum with a robust ability to degrade condensed tannins from Onobrychis viciifolia. This strain not only enhances the nutritional value of tannin-containing feeds but also holds potential application value in the field of fine chemicals.

Key words: condensed tannin, Onobrychis viciifolia, lactic acid bacteria, degradation rate, condition optimization