The factors determining effective probiotic activity – evaluation of survival and antibacterial activity of selected probiotic products: an in vitro study

Introduction
The purpose of this study was to evaluate osmotic stress resistance and survival during incubation in hydrochloric acid of bacteria contained in various market products of paediatric probiotics.

Material and methods
In the study first phase, the test specimens were incubated in different concentrations of hydrochloric acid simulating the stomach environment of infants and older children. The second part of the study involved exposing the probiotic microorganisms to osmotic stress conditions (incubation in 4% NaCl solution). In both phases of the study, the decrease in the number of viable microorganisms during the experiments was determined on a logarithmic scale and the survival rate was calculated.

Results
The best survival rate of probiotic bacteria was found in probiotic specimens containing the greatest diversity of bacterial strains and produced by microencapsulation technology. The lowest survival rate was found in probiotic specimens containing a single probiotic strain produced by traditional technology. Unquestionable differences in the survival rate of probiotic bacteria in specimens with the same diversity of probiotic strains produced by different technologies were shown.

Conclusions
The highest possible therapeutic effect can be expected from probiotic market specimens containing the highest diversity of bacterial strains and produced by microencapsulation technology. This technology guarantees probiotic bacteria’s greatest survival under negative acidic and osmotic stress conditions.