ProbiOmics: health and technological impacts caused in the metabolome of probiotic microorganisms submitted to stress conditions

Author(s)

Juliana Silva da Graça

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2021-05-06

Examining board members

Anderson de Souza Sant'Ana; Adriane Elisabete Antunes de Moraes; Edenir Rodrigues Pereira Filho; Severino Matias de Alencar; Patrícia Blumer Zacarchenco Rodrigues de Sá

• Advisor: Anderson de Souza Sant'Ana

Abstract

Fermented dairy products are widely consumed foods and are characterized as one of the main vehicles for the addition of probiotics. In recent years, a pre-submission or pre-cultivation of probiotics to stress conditions has been shown to be an effective practice in increasing the viability of these microorganisms during fermentation and drying processes. Although the application of pre-cultured probiotics to stress conditions in natural yogurts has been related to a change in the metabolome of these microorganisms, there are still no studies that demonstrate the impact of "stressed" or "adapted" probiotic cultures in nutritional aspects (such as in the bioaccessibility of vitamins and minerals) of natural or fortified fermented milk and yogurts. Given the above, the objective of this work was to study the effect of pre-submission of Lactobacillus acidophilus to stress conditions on growth kinetics, viability and metabolome generated during the production of natural fermented milks and fortified with orange by-product (source of minerals) or buriti pulp (source of carotenoids). And, later, to evaluate the impact of this addition on health-related effects and on the bioaccessibility of carotenoids provitamin A and calcium. The probiotic strain of L. acidophilus DSM 13241 was pre-submitted to oxidative, acid, and osmotic stress conditions, being subsequently inoculated into milk, in mono or co-culture with Streptococcus thermophilus and L. delbrueckii subsp. bulgaricus, for the manufacture of natural or fortified fermented milk and yogurts. The growth kinetics and viability of the cultures used were evaluated during the processing and shelf life of the manufactured products. The composition of volatile metabolites was evaluated by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The composition of non-volatile metabolites was evaluated by Nuclear Magnetic Resonance (NMR). The bioaccessibility of calcium and carotenoids was assessed by in vitro tests simulating, respectively, the dialysis and micellization of these compounds. And the bioaccessibility of carotenoids provitamin A and calcium and the impact of fortified fermented products on the activity of the endogenous antioxidant system, expression of endogenous stress response proteins (HSPs), composition of the fecal microbiota, and bone health were performed through an in vivo assay using healthy male Wistar rats (n = 6) for 60 days. The results demonstrated that the pre-submission of L. acidophilus to acid, oxidative, and osmotic stress conditions was responsible for altering the multiplication rate, the lag phase time, and in some cases the viability of the probiotic and starter cultures. The use of the "stressed" culture had an impact on the production of volatile compounds and on the bioaccessibility of calcium and carotenoids in the evaluated products. Besides, the in vivo test demonstrated that the consumption of fortified fermented products increased the absorption of vitamin A, expression of HSPs, and activity of the endogenous antioxidant system; in addition to in some cases modifying the relative abundance of certain genera present in the fecal microbiota, increasing the production of short-chain fatty acids and reducing the lipopolysaccharide blood content. In this way, the results of the present study demonstrate new findings regarding the application of probiotic microorganisms subjected to stress conditions in natural and fortified fermented products, increasing the understanding of the impacts resulting from their use, both in the characteristics related to the process and product and in the regards its nutritional and therapeutic value (AU)

• FAPESP's process: 16/12001-0 - Probiomics: health and technological impacts caused in the metabolome of probiotic microorganisms submitted to stress conditions
• Grantee: Juliana Silva da Graça
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)