Growth characteristic of probiotic in fermented coconut milk and the antibacterial properties against Streptococcus pyogenes

Abstract

This study investigated growth characteristics and antibacterial properties of probiotics in fermented coconut milk (CM) against Streptococcus pyogenes. A total of eight probiotics were screened for their survivability in CM. Antibacterial test against S. pyogenes was carried out on strain with highest growth rate. The survivability of probiotics in CM is strain dependent with S. salivarius ATCC 13419 showing the highest growth rate. Titratable acidity of the CM increased significantly while pH decreased significantly upon 9 h fermentation. The antibacterial properties of CM fermented with S. salivarius ATCC 13419 and K12 against S. pyogenes enhanced by 60.60% and 67.69%, respectively, compared to non-fermented CM. Their ability to metabolise carbohydrates and fats in CM was proven where alpha-glucosidase activity of S. salivarius ATCC 13419 and K12 was 22.42 ± 1.73 and 24.92 ± 7.22 unit/L, respectively, whereas, lipase activity was 1498.29 ± 48.50 and 1749.90 ± 254.28 unit/L, respectively. Lipolytic activity of these strains was further evidenced by GC-MS results whereby lauric acid content (potent antibacterial substance) in CM fermented with S. salivarius ATCC 13419 and K12 increased significantly by 5.03% and 10.74%, respectively. In conclusion, fermented CM provided a new alternative of non-dairy functional product with antibacterial potential against S. pyogenes.

Keywords: Antibacterial properties; Coconut milk; Fermentation; Probiotic.