SummaryThe benefi ts of probiotic bacteria have been widely explored. However, fermented foods and digestive system of humans and animals are an inexhaustible source of new potentially probiotic microorganisms. In this study we present three new Lactobacillus plantarum strains isolated from diff erent dairy products: cow′s cheese, sheep′s cheese and whey. In order to determine the antibacterial activity of yet unexplored L. plantarum strains against Salmonella enterica serotype Typhimurium, in vitro competition and co-culture tests were done. Furthermore, adhesion of these strains to Caco-2 cells and their infl uence on the adhesion of Salmonella were tested. Results showed the potential probiotic activity of isolated strains. L. plantarum strains survived in the presence of 1 % bile salts, they possessed acidifi cation ability, antibacterial activity and signifi cantly att enuated the growth of S. Typhimurium in brain heart infusion broth. All tested L. plantarum strains were able to adhere to Caco-2 cells and signifi cantly impair the adhesion of S. Typhimurium. All three L. plantarum strains exhibited signifi cant probiotic potential and anti-Salmonella activity; therefore, further testing on in vivo models should follow.

Introduction. Legionella longbeachae, a causative agent of Legionnaire's disease, has often been associated with potting soil and gardening, a feature quite distinct from other Legionella species. The precise transmission mechanism is still unknown, although due to the ecological coherence of the soil and water there is a potential risk of infection by contaminated stagnant water in the garden. Objective. The aim of the study was to explore the ability of L. longbeachae to survive in stagnant tap water usually used for watering in gardens. The influence of different factors (temperature, pH and NaCl concentration) on L. longbeachae survival in stagnant tap water was also tested. Results. The result showed that L. longbeachae is viable in stagnant tap water over 100 days at 4 °C and 25 °C. The survival of L. longbeachae exposed to different pH and NaCl concentration suggests resistance to low pH values (pH2 and pH5) and all tested NaCl concentrations at temperatures lower than 25 °C. The ability of L. longbeachae to persist in stagnant tap water should be taken seriously in the risk assessments as a possible hidden reservoir of infection.