Prebiotic Effect of Inulin Extract from Dahlia Tubers (Dahlia Pinnata L.) On the Growth Performance of Intestinal-origin Lactobacillus Casei AP.

Abstract

Background and Objective: A prebiotic is a non-digestible food component that supports the growth of probiotics in the gastrointestinal tract, thus providing beneficial effects to the host. One commercially available prebiotic is inulin, produced from Jerusalem artichokes and chicory. A previous study reported that the inulin from dahlia tubers is of better quality due to the presence of soluble and insoluble fibres. Due to its potential, inulin from dahlia tubers has been increasingly tested for its capability as a prebiotic. The aim of this study was to investigate the prebiotic effects of inulin and inulin extract from dahlia tubers on the viability of Lactobacillus casei AP and representative Enterobacteriaceae and to measure the prebiotic index and production of short-chain fatty acids. Methodology: This study focused on the combined effect of a prebiotic (inulin or inulin extract from dahlia tubers) and a probiotic, L. casei AP, which originated in a human gastrointestinal tract. This combination resulted in the growth suppression of pathogenic bacteria, the growth promotion of the probiotic and a high prebiotic index. The combination of L. casei AP and inulin/inulin extract, which was defined as a synbiotic, was also evaluated for the growth suppression of H. pylori and S. dysenteriae. Results: The L. casei AP had a higher growth rate in the presence of inulin extract or inulin than MRS did. Co-culturing E. coli and L. casei AP in media containing inulin extract suppressed the growth of E. coli and simultaneously resulted in the highest prebiotic index, at 4.70. The synbiotic effect of inulin extract together with L. casei AP was stronger in suppressing the growth of S. dysenteriae than of H. pylori. This inhibition was concomitant with the production of short-chain fatty acids, lactate, propionate, propionate and butyrate, which contributed to lowering the pH in the media. During fermentation, lactate was produced at the highest concentration (33.83-35.53%), followed by acetate (9.83-10.35%), propionate (0.05-0.45%) and butyrate (0.03-0.49%). Conclusion: Inulin extract from dahlia tubers acts very well as a prebiotic by supporting the growth of probiotic L. casei AP and suppressing the growth of the pathogens S. dysenteriae and H. pylori, resulting in a high prebiotic effect.