Efficacy of Salmonella Bacteriophage S1 Delivered and Released by Alginate Beads in a Chicken Model of Infection.

Modern bacteriophage encapsulation methods based on polymers such as alginate have been developed recently for their use in phage therapy for veterinary purposes. In birds, it has been proven that using this delivery system allows the release of the bacteriophage in the small intestine, the site of infection by Salmonella spp. This work designed an approach for phage therapy using encapsulation by ionotropic gelation of the lytic bacteriophage S1 for Salmonella enterica in 2% w/v alginate beads using 2% w/v calcium chloride as crosslinking agent. This formulation resulted in beads with an average size of 3.73 ± 0.04 mm and an encapsulation efficiency of 70%. In vitro, the beads protected the bacteriophages from pH 3 and released them at higher pH. To confirm that this would protect the bacteriophages from gastrointestinal pH changes, we tested the phage infectivity in vivo assay. Using a model chicken (Gallus gallus domesticus) infected with Salmonella Enteritidis, we confirmed that after 3 h of the beads delivery, infective phages were present in the chicken's duodenal and caecal sections. This study demonstrates that our phage formulation is an effective system for release and delivery of bacteriophage S1 against Salmonella Enteritidis with potential use in the poultry sector.

Long-term conservation of Tarenaya rosea (Cleomaceae) root cultures: histological and histochemical analyses during cryopreservation using the encapsulation-vitrification technique.

Adventitious root cultures of Tarenaya rosea were successfully cryopreserved using the encapsulation-vitrification technique. Histological analysis revealed useful information on the successive steps of cryopreservation. Coupled with complementary histochemical approaches, these studies provided cellular and tissue descriptions of T. rosea root cultures during cryopreservation and contributed to an understanding of cellular stress responses, as well as characterization of the anatomical pattern of root regeneration. The effects of exposure duration to PVS3 solution (0-120 min), unloading treatment (direct and gradual), and recovery medium (liquid and solid) on recovery of cryopreserved roots were investigated. The highest recovery (91%) after cooling in liquid nitrogen (LN) was reached with PVS3 treatment for 90 min, gradual rehydration in unloading solution, and recovery on solid MS medium. The cryopreserved roots showed high multiplication capacity, which was maintained for up to four subcultures. The effect of cryopreservation on root structure was investigated by histological and histochemical studies. Plasmolysis intensified during exposure to loading and PVS3 solutions, but decreased after unloading treatment. The proportion of intercellular spaces increased progressively throughout the cryopreservation protocol, culminating in root cortex disruption. Histochemical analyses revealed polysaccharides, proteins, and both lipidic and pectic substances in intercellular spaces. The vascular cylinder remained intact, ensuring the formation of new roots from the pericycle, showing that proliferative capacity of cryopreserved roots had not diminished.

Encapsulation of Lactobacillus fermentum K73 by Refractance Window drying.

The purpose of this work was to model the survival of the microorganism and the kinetics of drying during the encapsulation of Lactobacillus fermentum K73 by Refractance Window drying. A whey culture medium with and without addition of maltodextrin were used as encapsulation matrices. The microorganism with the encapsulation matrices was dried at three water temperatures (333, 343 and 353 K) until reaching balanced moisture. Microorganism survival and thin layer drying kinetics were studied by using mathematical models. Results showed that modified Gompertz model and Midilli model described the survival of the microorganism and the drying kinetics, respectively. The most favorable process conditions found with the mathematical modelling were a drying time of 2460 s, at a temperature of 353 K. At these conditions, a product with 9.1 Log CFU/g and a final humidity of 10% [wet basis] using the culture medium as encapsulation matrix was obtained. The result shows that Refractance Window can be applied to encapsulate the microorganism probiotic with a proper survival of the microorganism.