ENHANCEMENT OF SACCHAROMYCES CEREVISIAE GLUTATHIONE AND MICRONUTRIENTS CONTENT FOR NUTRACEUTICAL APPLICATIONS.
Tesi di Dottorato
Data di Pubblicazione:
2012
Citazione:
ENHANCEMENT OF SACCHAROMYCES CEREVISIAE GLUTATHIONE AND MICRONUTRIENTS CONTENT FOR NUTRACEUTICAL APPLICATIONS / A. Musatti ; tutor: M. Manzoni, M.S. Rollini ; coordinatore: M. A. Pagani. Universita' degli Studi di Milano, 2012 Feb 27. 24. ciclo, Anno Accademico 2011. [10.13130/musatti-alida_phd2012-02-27].
Abstract:
This Ph.D. research concerns nutritional and microbiological aspects, and the final aim of this project is the development of innovative food supplements formulations containing Saccharomyces cerevisiae, enriched, by biotechnological processes, with micronutrients and antioxidant molecules.
This idea was supported by the fact that even if in the developed world a clinical deficiency of micronutrients is uncommon, a suboptimal intake of certain micronutrients has been linked with an increased risk of chronic diseases such as CVD (cardiovascular disease) and cancer; moreover external factors, such as smoke, UV radiations and pollution contribute to oxidative stress and to the formation of free radicals that are considered to contribute to the risk of cancer. In this context and to contain cellular damage, an important role has recently been attributed to the possible use of molecules with antioxidant activity, such as glutathione.
The yeast S. cerevisiae is one of the most studied microorganisms and is considered a model for eukaryotes. It is used both in industrial productions and in human diet. As well as leavening agent for baking products and fermenting agent for alcoholic beverages such as wine and beer, S. cerevisiae is used in the industrial production of ethanol, enzymes and dried yeast both for animal-feed and food supplement (Directive 2002/46/EC).
Subsequently to the identification of some potential molecules, with which the yeast might be enriched, the research focused mainly on cell enrichment with reduced glutathione (GSH) and metal-conjugated glutathione, with particular regard to the set-up of biotechnological processes in order to increase product yields. The research also investigated the biological activity of the obtained enriched biomass, in particular the fate of GSH when the biomass is swallowed, by investigating GSH stability during gastric digestion and any possible protective role of the yeast cell, and by analysing GSH transport/absorbtion by intestinal cell lines and any possible toxicity.
In the first year of the research numerous trials were carried out in order to increase intracellular GSH levels in S. cerevisiae both during cell growth and applying a post-growth procedure, identified as “activation”. The best results were obtained applying this second approach in which glucose, GSH precursors (cysteine CYS, glycine GLY and glutamic acid GLU), together with cofactors, were dissolved in a solution in which yeast cells were suspended. In this experimental phase the activation attitude of two different commercial forms of the yeast, compressed or dried, were evaluated. Results highlighted that, even though they generally performed similarly in bread-making process and possessed similar initial intracellular GSH levels (about 0.6% dcw) and for both of them higher yields were obtained during the first 24 h of activation, they evidenced different attitudes towards the tested activation mix. In particular, dried yeast samples reached high GSH levels (1.24 ±0.08% dcw) with the mix CYS-GLY-GLU, while the compressed yeast also with the CYS-GLY-SER (with serine) (1.44 ±0.12% dcw). Concerning the influence of the energy source, the dried form did not appear sensitive to the over-presence of glucose, while the compressed yeast form showed different sensitivity to glucose addition, depending on the type of the mixture employed. Glucose addition in CYS-GLY and CYS-GLY-GLU mixtures (in particular at 4 h) increased GSH yields of about 30-40% with respect to the control sample. No increase was evidenced employing the CYS-GLY-SER mixture.
The possibility of obtaining GSH directly in extracellular form was also investigated; this approach can represent an interesting opportunity of reducing GSH production
Tipologia IRIS:
Tesi di dottorato
Keywords:
glutathione ; Saccharomyces cerevisiae ; copper ; food supplement ; Design of Experiments ; bioavailability
Elenco autori:
A. Musatti
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