• probiotics
• Bacillus clausii

Probiotics are living microorganisms that, when administered in adequate amounts, confer a health benefit to the host. The principal probiotics formulations are constituted by single species or mixtures of different species belonging to the genera Lactobacillus, Streptococcus, Bifidobacterium, Bacillus and Saccharomyces. The use of spore-forming Gram-positive bacilli, like Bacillus clausii, offers the advantages typical of spore-based preparations, such as a long lasting stability and vitality and resistance to the adverse conditions that the germs encounter during transit in the stomach. Although, these microorganisms are used very frequently in commercial products, little is known about beneficial properties that they can exert in the host. The aim of this thesis was to evaluate some potential beneficial effects of different strains of B. clausii. To this purpose, we analyzed four B. clausii strains (T, OC, SIN, NR) for i) their ability to survive in artificial intestinal fluid; ii) production of enzymes with antioxidant activity, such as superoxide dismutase (SOD) and catalase (CAT), and of β-galactosidase, an enzyme involved in the degradation of lactose; iii) secretion of vitamin B2 (riboflavin); iv) ability to adhere to mucins; and v) production of D-lactate.
The results obtain indicated that the analyzed strains can survive in the simulated intestinal environment for up to 8 hours, showing a high tolerance to the simultaneous presence of bile salts and pancreatin. The strains were found to be capable of producing SOD, CAT, β-galactosidase and riboflavin, suggesting that the administration of these microorganisms as probiotics could be of some help in the reduction of oxidative stress, for a better tolerance to lactose, especially in intolerant subjects, and in vitamin intake. Furthermore, the strains were found to be unable to produce D-lactate during growth in vitro, suggesting that their administration does not increase the risk of developing D-lactic acidosis in the host. Adhesion to the intestinal mucosa by probiotic microorganisms is an essential feature for the interaction with the host, as it is necessary to promote the persistence of these microorganisms in the intestinal environment. Results of the in vitro adhesion studies revealed that B. clausii can adhere to mucins both in aerobic and anaerobic conditions.
In conclusion, the overall results herein obtained indicate that B. clausii possesses many properties that can support its use as probiotic.