Abstract:A lactic acid bacterium with high angiotensin-I converting enzyme (ACE)-inhibitory activity was screened from 31 isolates obtained from traditional fermented foodsin Yunnan. The isolates were preliminarily screened by ultraviolet (UV) spectrophotometry, followed by high-performance liquid chromatography (HPLC). Potential probiotic properties and dynamic changes in ACE inhibitory activity during skim milk fermentation were evaluated. Lactobacillus plantarum YM-4-3 strain was selected owing to its high ACE inhibitory activity, broad antibacterial spectrum, sensitivity to antibiotics, and strong tolerance to acid and bile. The inhibition zone diameters of Lactobacillus plantarum YM-4-3 against Escherichia coli O157:H7 and Listeria monocytogenes were 41.30 and 42.00 mm, respectively.After treatment with strong acid (pH 2.5) and high concentration of bile salt (0.3%), the viable cell count was still above 105 CFU/mL. The dynamic monitoring of ACE inhibitory activity of Lactobacillus plantarum YM-4-3 during the fermentation of skim milk indicated that the optimum condition for Lactobacillus plantarum YM-4-3 to produce ACE inhibitory peptide was 37 ℃ for 48 h. Under this condition, the ACE inhibition rate of fermented milk reached 81.23%, and the maximum biomass of the strain and the highest content of free amino acid and polypeptides in fermented milk were achieved. This study can provide a theoretical basis and a candidate bacterium for the study and development of a novel, functional fermented milk beverage, with high ACE inhibitory activity.
