"Physicochemical, immunomodulatory and safety aspects of milks fermented with Lactobacillus paracasei isolated from kefir".

The use of Lactobacillus paracasei strains isolated from kefir grains as starters for the development of functional dairy products was evaluated. The physicochemical and immunomodulatory properties of milks fermented with L. paracasei CIDCA8339, CIDCA83123 and CIDCA83124 were analyzed. The three strains produced bioactive metabolites during fermentation, since the fermented milk supernatants were able to downregulate >75% of the induced innate immune response in vitro. Although all strains presented absence of hemolytic activity and susceptibility to antibiotics, L. paracasei CIDCA8339 presented more attractive probiotic and technological properties. Mice consuming the fermented milk with L. paracasei CIDCA 8339 did not present significant modifications in sIgA levels or TNF-α, TGF-ß and IL-10 mRNA expression in ileum. Additionally, a decrease of INF-γ level in ileum and no microbiological translocation to liver and spleen was observed. These results demonstrate that L. paracasei CIDCA8339 represents a safe promising potential probiotic strain for the development of functional foods.

Microencapsulation of Lactic Acid Bacteria Improves the Gastrointestinal Delivery and in situ Expression of Recombinant Fluorescent Protein.

The microencapsulation process of bacteria has been used for many years, mainly in the food industry and, among the different matrixes used, sodium alginate stands out. This matrix forms a protective wall around the encapsulated bacterial culture, increasing its viability and protecting against environmental adversities, such as low pH, for example. The aim of the present study was to evaluate both in vitro and in vivo, the capacity of the encapsulation process to maintain viable lactic acid bacteria (LAB) strains for a longer period of time and to verify if they are able to reach further regions of mouse intestine. For this purpose, a recombinant strain of LAB (L. lactis ssp. cremoris MG1363) carrying the pExu vector encoding the fluorescence protein mCherry [L. lactis MG1363 (pExu:mCherry)] was constructed. The pExu was designed by our group and acts as a vector for DNA vaccines, enabling the host cell to produce the protein of interest. The functionality of the pExu:mCherry vector, was demonstrated in vitro by fluorescence microscopy and flow cytometry after transfection of eukaryotic cells. After this confirmation, the recombinant strain was submitted to encapsulation protocol with sodium alginate (1%). Non-encapsulated, as well as encapsulated strains were orally administered to C57BL/6 mice and the expression of mCherry protein was evaluated at different times (0-168 h) in different bowel portions. Confocal microscopy showed that the expression of mCherry was higher in animals who received the encapsulated strain in all portions of intestine analyzed. These results were confirmed by qRT-PCR assay. Therefore, this is the first study comparing encapsulated and non-encapsulated L. lactis bacteria for mucosal DNA delivery applications. Our results showed that the microencapsulation process is an effective method to improve DNA delivery, ensuring a greater number of viable bacteria are able to reach different sections of the bowel.