Objective: Bacteriocin production is proposed as an important factor in the beneficial effect of probiotics. The present study used encapsulation technology to improve bacteriocin-producing Pediococcus acidilactici HM-2 survivability under in vitro gastrointestinal conditions and evaluate its impact in vivo on gastrointestinal transit and gut microbiota modulation.

Materials and Methods: Bacteriocin produced by P. acidilactici HM-2 was purified by chromatographic techniques and identified according to its molecular mass and gene sequencing. Encapsulation was carried out using alginate, and capsules were then coated with whey proteins using the lyophilized extrusion method. A Scanning Electron Microscope (SEM) was used to study the surface and core structure of capsules. The effect of encapsulation on probiotic viability and transit under either simulated or in vivo conditions was evaluated using microbiological and molecular assays. Furthermore, the impact of either encapsulated (E) or non-encapsulated (NE) P. acidilactici in mice gut microbiota was determined using quantitative Polymerase Chain Reaction (qPCR) and Denaturing Gradient Gel Electrophoresis (DGGE).

Results: Mass spectrometry analysis and the sequence of the amplified pediocin gene identified the bacteriocin as a pediocin PA-1. Encapsulation improves probiotic viability in vitro but does not modify the gut transit time of the probiotic strain in mice. Interestingly, the two probiotic forms (E and NE) significantly increased Bifidobacterium spp. In addition, the E form also increased the Bacteroidetes (Bacteroides and Prevotella) and Lactobacillus murinus and Lactobacillus acidophilus species.

Conclusions: P. acidilactici HM-2, a pediocin PA-1 producer, could modify some gut microbiota groups in mice depending on encapsulated or non-encapsulated forms of administration.