Sporopollenin Exine Microcapsules as Potential Intestinal Delivery System of Probiotics.

Despite several decades of research into encapsulation of bacteria, most of the proposed technologies are in the form of immobilized cultures. In this work, sporopollenin exine capsules (SECs) opened, using silica particles which act as pressing micro-probes, and loaded with Lactobacillus casei (L. casei) cells, are described for the first time. The proposed encapsulation provided ≈30× higher encapsulation yield (30.87%), compared to direct compression of SECs (0.99%). Encapsulated L. casei cells show 1.21- and 2.25-folds higher viability compared to free cells, in in vitro simulated fasted and fed media representing the human gastrointestinal (GI) tract, respectively. Encapsulated L. casei can proliferate inside the SECs, generating enough pressure to cause the SECs to burst and release the viable and metabolically active cells. The noticeable difference with the application of the SECs as a means of encapsulation is that the SECs may act as a bioreactor and provide time for the encapsulated cells to multiply thousands of times before being released, following the SEC's burst. The unique advantages of SECs alongside the proposed encapsulation method, demonstrates the potential application of SECs as delivery system of probiotics to the distal part of the human GI tract.

High level of heterogeneity among Listeria monocytogenes isolates from clinical and food origin specimens in Greece.

In order to examine the genetic variation of clinical and food isolates of Listeria monocytogenes in Greece, a total of 61 L. monocytogenes non-duplicate isolates, recovered from clinical specimens (n=19) and food (n=42), were serotyped and genotyped using two different Random Amplification of Polymorphic DNA (RAPD) protocols and Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Serotype group 4b, 4d, 4e prevailed (39.4%), among both clinical and food isolates, followed by serotype group 1/2a, 3a (23.0%), which nevertheless was detected only among food isolates. The most discriminatory typing protocol was MLVA, which grouped four isolates into two pairs, while the remaining isolates produced unique fingerprints. Similar results were obtained when taking into account the combination of the two RAPD protocols (Simpson index 0.999); six isolates were grouped into three pairs, two of which were the pairs that were identified also by MLVA. Single use of each RAPD protocol resulted in inferior discrimination (Simpson index 0.978 and 0.997, respectively). In conclusion, the two molecular procedures, MLVA, and the combined RAPD protocols, produced similar results, showing that L. monocytogenes isolates from clinical and food specimens were highly heterogenous and that clustering was very uncommon.

Improvement of oleuropein extractability by optimising steam blanching process as pre-treatment of olive leaf extraction via response surface methodology.

Impact of steam, hot water blanching and UV-C irradiation as pre-treatments on extraction of oleuropein and related biophenols from olive leaves (OLs), was investigated. Moreover, particle size effect of olive leaves and steam blanching duration were selected as independent variables to optimise steam blanching process in terms of oleuropein content (OC) and antioxidant activity (AC) of ethanolic extracts, by using response surface methodology. Optimum conditions for OC and AC were 10 min steam blanching of 20-11 and 3-1mm olive leaf fraction, respectively. Depending on the extraction procedure, at optimum conditions of steaming the results indicate that steam blanching of OL prior to extraction can significantly increase oleuropein yield from 25 to 35 times compared to non-steam blanched sample, whereas the antioxidant activity increased from 4 to 13 times. No significant UV-C effect was observed in OC and AC, while hot water blanched samples showed significantly higher oleuropein yields and antioxidant activity compared to untreated samples.