Aktivitas antibakteri kombinasi susu probiotik lactobacillus bulgaricus dan streptococcus thermophilus terhadap bakteri penyebab diare

Fermented milk of Lactobacillus bulgaricus and Streptococcus thermophilus were combined in nine ratio (1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1, v/v) which were examined their antibacterial activity against Escherichia coli, Salmonella typhimurium, and Vibrio cholerae. The antibacterial activity were conducted by Kirby Bauer method. Combination of fermented milk of Lactobacillus bulgaricus and Streptococcus thermophilus in ratio 1:9 showed the highest inhibition zone against E. coli, S. typhimurium, and V. cholera with diameters of 12.97 ± 0.25 mm, 12.27 ± 0.51 mm, and 12.70 ± 0.10 mm respectively. The inhibition zones diameter of combination ratio 1:9 of fermented milk were not significantly different (p>0.05) from inhibition zone diameter of the combination ratio 2:8 and also were not significantly different (p>0.05) from inhibition zone diameter of fermented milk with Streptococcus thermophilus against V. cholerae, E. coli and S. typhimurium respectively. Minimum inhibitory concentration of the combination of fermented milk (ratio 1:9) against E. coli, S. typhimurium and V. cholera were reached by dilution 60% and 40% (v/v) respectively