Recombinant Lactococcus lactis expressing haemagglutinin from a polish avian H5N1 isolate and its immunological effect in preliminary animal trials.

Lactic acid bacteria (LAB) are Gram-positive, non-pathogenic microorganisms that are gaining much interest as antigen producers for development of live vaccine vectors. Heterologous proteins of different origin have been successfully expressed in such LAB species as Lactococcus lactis. Recombinant L. lactis strains have been shown to induce specific local and systemic immune responses against various antigens. Our study aimed at constructing a L. lactis strain expressing haemagglutinin of the Polish avian H5H1 influenza isolate and examining its effect on animals. Expression of the cloned H5 gene was achieved using the nisin-controlled gene expression system. Detection of the intracellular H5 antigen produced in L. lactis was performed by Western blot analysis and confirmed using Mass Spectrometry. The potential of L. lactis recombinant cells to induce an immune response was examined by setting up preliminary immunization trials on mice and chicken. Obtained sera were tested for specific antibodies by ELISA assays. The results of these preliminary studies are a promising step toward developing a vaccine against the avian bird flu using Lactococcus lactis cells as bioreactors for efficient antigen production and delivery to the mucosal surface

Molekularne mechanizmy oporności bakterii kwasu mlekowego na bakteriofagi.

Lactic acid bacteria (LAB) constitute a heterogeneous group of bacteria, which are found in diverse environments, such as the human body or plants, and are traditionally used to produce fermented food. Food bio-transformation in industrial processes increases the economical importance of LAB. However, conditions that exist in industrial facilities do not seem to be an optimal environment for bacteria. During technological processes, which take place in enclosed space, the intensity of physical (temperature shift), chemical (acids) or biological (phages) stress factors raises dramatically. In the dairy industry, bacteriophage contamination is regarded as a serious problem due to the disturbance or arrest of the production processes, which results in significant economical losses. It is well documented that LAB evolved defense systems against bacteriophages, which allow them to survive in harsh conditions. Therefore, bacteria used in food industry are selected for high level of bacteriophage resistance. According to the mode of action, natural bacterial defense systems against their predators were divided into 5 categories: (i) inhibition of phage adsorption, (ii) blocking of phage DNA injection, (iii) phage abortive infection systems, (iv) restriction modification systems, (v) CRISPR/Cas systems. Remarkably, the majority of known bacteriophage resistance systems are plasmid-encoded. In this context, future studies on phage resistance mechanisms as well as plasmid sequencing may have an impact on solving the problem of phage infections in the dairy industry

Potential of Lactobacillus plantarum IBB3036 and Lactobacillus salivarius IBB3154 to persistence in chicken after in ovo delivery

The aim of this study was to characterize and compare selected Lactobacillus strains originating from different environments (cow milk and hen feces) with respect to their applicative potential to colonize gastrointestinal track of chickens before hatching from an egg. In vitro phenotypic characterization of lactobacilli strains included the investigation of the important prerequisites for persistence in gastrointestinal tract, such as a capability to survive in the presence of bile salts and at low pH, enzymatic and sugar metabolic profiles, adhesion abilities, and resistance to osmolytes, temperature, and antibiotics. Regarding the resistance of lactobacilli to most of the various stress factors tested, the milk isolate Lactobacillus plantarum IBB3036 showed better abilities than the chicken feces isolate Lactobacillus salivarius IBB3154. However, regarding the acidification tolerance and adherence ability, L. salivarius IBB3154 revealed better characteristics. Use of these two selected lactobacilli isolates together with proper prebiotics resulted in the preparation of two S1 and S2 bioformulations, which were injected in ovo into hen Cobb500 FF fertilized eggs. Furthermore, in vivo tests assessing the persistence of L. plantarum IBB3036 and L. salivarius IBB3154 in the chicken gastrointestinal tract was monitored by PCR‐based classical and quantitative techniques and revealed the presence of both strains in fecal samples collected 3 days after hatching. Subsequently, the number of L. salivarius IBB3154 increased significantly in the chicken intestine, whereas the presence of L. plantarum IBB3036 was gradually decreased