Akkermansia muciniphila and delivery systems to promote gut health

Abstract

In the last years, Akkermansia muciniphila has emerged as a next-generation probiotic, given its demonstrated relevant biological activities in several intestinal and extra intestinal disorders. Furthermore, one of the major challenges for industry has been to develop effective delivery systems to ensure its high probiotic viability during manufacturing, product shelf-life and after consumption, namely throughout the gastrointestinal passage. Based on the above, this thesis aimed to evaluate the potentiality of A. muciniphila to promote gut health, through a phenotypic characterization of certain probiotic properties, and to develop delivery systems that promote the viability of this probiotic throughout refrigerated aerobic storage and when exposed to simulated gastrointestinal conditions. Firstly, a phenotypic characterization of A. muciniphila DSM 22959 strain was performed, concerning the following probiotic properties: hydrophobicity, aggregation abilities and improvement of intestinal barrier function. In this analysis, this strain showed low cell-surface hydrophobicity, whereas auto-aggregation and co-aggregation percentages were similar to those obtained for Lacticaseibacillus rhamnosus GG, positive control strain. Regarding the intestinal barrier integrity assay, no conclusions could be drawn due to the need for optimization of the protocol used, however there is an apparent bias of A. muciniphila against the harmful effect of E. coli under the conditions tested. Upon phenotypic characterization, encapsulation via extrusion and a dairy food vector were explored as technological strategies to enhance viability and stability of A. muciniphila during refrigerated aerobic storage and when submitted to gastrointestinal transit. Indeed, A. muciniphila was successfully encapsulated in a calcium-alginate matrix via extrusion (60% yield) and exhibited a high stability in viability (ca. 108 CFU/g) after 28-days of refrigerated aerobic storage. Moreover, as storage time increased, encapsulated A. muciniphila demonstrated higher viability and stability under gastrointestinal conditions when compared to its free counterpart. The incorporation of A. muciniphila in a dairy matrix based on 77% (m/m) “Requeijão” and 23% (m/m) Greek style yogurt, originated a probiotic cheese spread with high microbiological quality, low total phenolic content (around 0.36 mg gallic acid equivalents/g of dried cheese) and interesting biological activities, namely antidiabetic (98.10% of α-glucosidase inhibition) and antihypertensive (49.18% of Angiotensin Converting Enzyme inhibition) properties. Simultaneously, this novel food ensured a high A. muciniphila viability level (> 108 CFU/g) during 21-days at 4ºC in aerobiosis and when exposed to gastrointestinal conditions. Additionally, this probiotic cheese displayed a similar profile in terms of texture, color, water activity and pH, when compared with cheese control/without bacteria, suggesting a potentially high acceptability among consumers. In conclusion, both extrusion in calcium-alginate matrix and incorporation into cheese spread seem to be promising strategies to safeguard A. muciniphila viability during refrigerated aerobic storage and detrimental gastrointestinal conditions.

Date of Award	2 Oct 2023
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Daniela Machado (Supervisor), Ana Maria Gomes (Co-Supervisor) & Joana Cristina Barbosa (Co-Supervisor)