Effect of inulin extracted from chicory and Jerusalem artichoke on bile tolerance and inhibition of two Lactobacillus species against E.coli O157:H7

Probiotics and prebiotics play important role in improvement of the intestinal microbial balance and have a great potential for food industry and public health. Survival of probiotics during gastric stress is influenced by the prebiotic carriers. In order to introduce effective synbiotic pairs, in this study the prebiotic influence of inulin (extracted from chicory and Jerusalem artichoke and also standard lab grade inulin), glucose and non-carbohydrate sample were assessed on bile resistance and inhibition of two Lactobacillus species against E.coli O157:H7. The effect of inulin treatments were studied on growth and viability of Lactobacillus casei PTCC 1608 and Lactobacillus rhamnosus PTCC 1637 under various bile salts concentrations (0, 0.3, 0.5, 1, 1.5%) in completely randomized factorial design and the inhibition effects were evaluated using well- diffusion technique in completely randomized design, and compared with controls. Results indicated that extracted inulin could be effective on enhancing the bile salts resistance of two lactobacilli. This effect was decreased by increasing in bile concentration while longer inulin chains had less effect compared to glucose. Although the most antimicrobial effects belonged to glucose, standard and chicory inulin showed acceptable antimicrobial effects as well. Inulin from Jerusalem artichoke with the highest degree of polymerization showed the least effects.