Impact of an anthocyanin rich extract upon probiotic and probiotic/human cell systems

Abstract

Blueberries have long been known to possess several biological properties, such as antimicrobial, antioxidant and anti-inflammatory activity, which are beneficial for human health. One of the latest additions to the list of blueberries known properties has been intestinal microbiota modulation. Considering that an anthocyanin rich blueberry extract has been previously shown to be capable of modulating pathogenic microorganisms adhesion in an in vitro adhesion model, this work sought to understand how the same extract would impact upon known probiotics’ metabolism and how these microorganisms’ metabolites would affect intestinal cell’s viability and modulate bacterial adhesion to intestinal cells. To do so, a three-step approach was drawn. In the first step, the extract’s capability to interfere in the fermentative process of four different probiotic bacteria, as well as a mixture of those, was evaluated through determination of total viable counts, organic acid production and sugar consumption. Secondly, the supernatants resulting from the fermentation in the presence or absence of extract were recovered and studied to see if they exerted any negative impact upon the viability of a cell line resembling the intestinal epithelium, namely Caco-2 cells. Lastly, and keeping in this line of thought, the effect of the extract upon probiotic bacteria (Lactobacillus rhamnosus R11 and B. animalis subsp. lactis BB12) adhesion to intestinal cells, (namely Caco-2 and the mucus producing HT29-MTX) was assayed. From a fermentation standpoint, the results obtained showed that the extract did not inhibit the growth of the bacteria tested (although the Lactobacillus tested had slightly lower viable counts in the presence of extract than the Bifidobacterium), and stimulated acid production which was significantly higher in its presence. When considering the fermentation supernatants’ impact upon Caco-2’s viability, the extract supernatants had an overall lower impact upon the cell’s metabolism, with lower metabolic inhibitions being observed. Additionally, supernatants fermented by Bifidobacterium animalis subsp. lactis BO appeared to promote cellular metabolism. Lastly, when evaluating the effect of the extract upon bacterial adhesion to the selected cellular models, it was possible to see that the presence of extract resulted in higher relative adhesion percentage values, and the Bifidobacterium tested had higher adhesion values for both cell lines in the presence of extract, which stands in accordance with reports that claim bifidogenic activity is enhanced in the presence of phenolic compounds.

Date of Award	21 Sept 2018
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Maria Manuela Pintado (Supervisor) & Sara Silva (Co-Supervisor)