Effects of Garcinia mongostana, Lycium barbzarum, Momordica grosvenori, and Psidium guajava on the Growth of Lactobacillus spp. and Streptococcus thermophilus

There are an increasing number of fermented beverage using herbal extract as a natural ingredient. The growth of bacteria in four plant water extract (Lycium barbarum, Psidium guajava, Momordica grosvenori, and Garcinia mongostana) as measured by the increase in turbidity of MRS and M17 growth medium containing Lactobacillus spp. and Streptococcus thermophilus respectively was investigated during 30 minutes of incubation at 37°C. The stimulatory effects on Lactobacillus spp. growth was tremendously enhanced (p<0.05) by L. barbarum (3.0%; OD=0.1.1) and P. guajava (1.5% (OD=0.5) and 3.0% (OD=0.6); respectively) compared to control (0%) after 30 minutes. In addition, inclusion of P. guajava (1.5%) shorted incubation time to reach plateau at 5 minutes. The inclusion of M. grosvenori and G. mangostana water extract at 0.30% increased Lactobacillus spp. growth by 2 and 14 fold respectively which higher than control. There was a dose response effect of all plant water extracts except for M. grosvenori on the growth of S. thermophilus. All the three concentrations of L. barbarum and P. guajava stimulated the growth of S. thermophilus which reach 3 fold higher than control at 1.5% L. barbarum. On the other hand, M. grosvenori water extract showed inhibitory effects on the growth of S. thermophilus at all doses but after the first 15 min at 3.0% the inhibitory effects were lost (p<0.05). G. mangostana water extract at 3.0% increased S. thermophilus growth 10 fold higher than control after 30 minutes. In conclusion, all plant water extract samples except M. grosvenori could be a good vehicle for carrying Lactobacillus ssp. and S. thermophilus while M. grosvenori could enhance the growth of Lactobacillus spp. but not S. thermophilus.