Evaluation of two Bacillus subtilis strains isolated from Korean fermented food as probiotics against loperamide-induced constipation in mice

Probiotics are live microbes that confer health benefits on the host when administered in adequate amounts. To evaluate the probiotic potential of Bacillus subtilis isolated from Korean fermented foods, we investigated the resistance to biological barriers and improvement of loperamide-induced constipation. The values of resistance to gastric acidity of B. subtilis CBD2 and KMKW4 strains were 55.34±2.12 and 64.58±2.95%, respectively, whereas the survival rate of B. subtilis KMKW4 (31.17±5.78%) in bile acids was superior to that of CBD2 (8.62±2.09%). These strains also demonstrated adhesiveness to intestinal epithelial HT-29 cells and an inhibitory activity against pathogenic microflora. Furthermore, B. subtilis CBD2 and KMKW4 strains improved gastrointestinal activity when tested in a loperamide-induced mouse model of constipation. Pre-treatment with CBD2 and KMKW4 strains before the onset of constipation improved fecal output and gastrointestinal transit in loperamide-treated mice. These strains also showed inhibitory effects on the activity of β-glucosidase and tryptophanase, harmful enzymes of intestinal microflora. Taken together, these finding show that B. subtilis CBD2 and KMKW4 have high adaptability to gastrointestinal environment, and the ability to inhibit pathogenic microflora and prevent constipation, suggesting their activity as potential probiotics.