Abstract: Objectives:Screening of high-yield DPP-4 inhibitors fermentation strains,identification of strains and study of fermentation characteristics. Methods:Using the screening model for DPP-4 inhibitors,the strains with DPP-4 inhibitory activity were screened by the stepwise dilution method from the traditional fermented food in Jiangnan. The strains were observed and analyzed by morphological,physiological and biochemical and 16S rRNA genes,to alignment to determine its relationship between species. Based on the DPP-4 inhibitory activity,the main research contents were compared with other lactic acid bacteria,selection of different culture media,optimization of fermentation conditions,and fermentation characteristics in skim milk(SKM)medium. Results:A strain of Paenibacillus polymyxa BD3736 was screened from the 11 strains with milk protein hydrolysis ability from Jiangnan traditional sour bean juice. The inhibition rate of DPP-4 of P. polymyxa BD3736 was fermented in 10%(W/V)skim milk(SKM)medium for 2 days under anaerobic condition was 66.4%±2.9%. Its inhibitory activity was much larger than Lactobacillus,Bifidobacterium and Streptococcus. The strain BD 3736 reached a peak of 1.05×10⁹ CFU/mL in 10%(W/V)SKM liquid medium at 30 ℃ and 180 r/min for 12 h,and the pH of system was 5.58. Under the same fermentation conditions,the inhibition rate of DPP-4 of the supernatant of the strain BD3736 for 2 days was 90.6%±2.6%,and the IC₅₀ value was(14.2±2.0) mg/mL. This study provides theoretical guidance and technical support for the further development of new oral hypoglycemic drugs or functional food ingredients with low side effects.