| 要約: | Lactic acid bacteria are some of the dominant bacteria in the rumen, and they have a high ability for lactic acid production. The present study aimed to screen and evaluate the performance of culturable rumen bacteria from Chinese Holstein dairy cows as a potential probiotic or inoculant for silage production, in order to isolate ruminal lactic acid bacteria and evaluate their potential as probiotics. Three strains of <i>Enterococcus avium</i> (<i>E. avium</i>, EA1-3); three strains of <i>Streptococcus lutetiensis</i> (<i>S. lutetiensis</i>, SL1-3); and six strains of <i>Streptococcus equinus</i> (<i>S. equinus</i>, SE1-6) were successfully identified from the rumen fluid using modified De Man Rogosa sharp medium supplemented with 0.325% lactic acid. <i>E. avium</i>, <i>S. lutetiensis</i> and <i>S. equinus</i> are clustered in the phylogenetic tree. All the 12 Gram-positive strains reached the plateau growth phase in 6–10 h, with an OD600 at about 1.8. Both gas and acid accumulation reached plateaus at about 10–12 h in all strains, and <i>S. equinus</i> showed the strongest capacity. The highest lactic acid accumulation was detected in <i>S. equinus</i> broth (up to 219.77 μmol/L). The growth of all isolates was inhibited at pH 4.0, and EA2, SL1, SL2, SL3 and SE2 were tolerant to 0.1%, 0.2% and 0.3% bile salt. In addition, the supernatants of the strains had inhibitory effects on <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. Specifically, the <i>S. equinus</i> strains exhibited the strongest inhibition of the pathogens. In conclusion, these 12 strains had good potential as silage inoculants or probiotics for edible animals, especially <i>S. equinus</i>.
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