Abstract: This study was aimed to explore the microbial source of α-glucosidase inhibitor and to screen bacterial strains with hypoglycemic effect.A Paenibacillus bovis BD3526 with high inhibitory activity against α-glucosidase was isolated from raw yak milk collected in Tibet via primary and secondary screening by means of in vitro model.The supernatant of the fermented skim milk by the strain P. bovis BD3526 demonstrated a strong inhibitory activity to α-glucosidase (＞60%) and was significantly higher than other tested bacterial isolates including some lactic acid bacteria.The ability of BD3526 to produce α-GI was genetically stable;furthermore,moderate cultivation temperature and aeration were beneficial for the strain BD3526 to accumulate the active components against α-glucosidase.The total viable counts reached a peak of 1.75×10⁹ CFU/mL for 12 h fermentation and the α-glucosidase inhibitory of fermented milk 6 h after inoculated maintained a high level (＞80%).However,constantly decreased IC₅₀ value showed that α-GI was further accumulated with the deepening of fermentation degree.

Key words: in vitro model, Paenibacillus bovis, screening, &alpha, -glucosidase inhibitor, skimmed milk