Lactobacillus gasseri within the Lactobacillus acidophilus group is a major species in the human microflora. The potential probiotic properties of a L. gasseri strain of human origin were evaluated. Out of 17 studied L. gasseri strains, L. gasseri 4/13 showed the highest immunomodulatory effect (induction of interferon gamma measured by sandwich enzyme-linked immunosorbent assay) in Balb/c mouse splenocytes in vitro and the highest rate of adhesion to Caco-2 human epithelial cells. The strain also reduced the concentration of cholesterol in the growth medium by 65% as compared with the initial concentration (measured spectrophotometrically). These probiotic properties indicate that L. gasseri 4/13 could prove an attractive concentrated adjunct monoculture in the production of new functional foods. To obtain a freeze-dried bacterial concentrate from L. gasseri 4/13, the influence of different culture media, temperatures and pH values on the accumulation of cell biomass was studied. Yoghurt samples were produced using a classical fermentation technology. Freeze-dried concentrated monoculture of L. gasseri 4/13 with over 1 × 1010 CFU/g viable cells was added as an adjunct culture together with a starter. The viable L. gasseri 4/13 cells remained above the critical value of 106 CFU/g during storage at 5 °C for the entire 20-day period. Organoleptic tests did not reveal any adverse change in the product taste and aroma of yoghurt samples at the 20th day. In conclusion, L. gasseri 4/13 was selected as having suitable probiotic and cultural characteristics for production of fermented milk products with high nutritional and biological value.
Keywords: Lactobacillus gasseri; cultural characteristic; probiotic properties; yoghurt.