ABSTRACTS – ORAL PRESENTATIONS - AMCA, spol. s r.o.

concentrations 0.15, 0.2, 0.3 and 0.5 %. From the technological procedures used during
the cheese production have been tested the effects of temperature (58 and 70 ° C) and
high concentration of NaCl (5 M). Two strains of lactobacilli were used for the trials -
exopolysaccharides (EPS) producing strain L. reuteri and EPS non-producing L. casei. To
assess the viability of lactobacilli in the gastric juice, in a NaCl solution and under the
influence of temperature was used propidium iodide (PI) staining. Due to the non-specific
reaction between PI and bile salts viability was assessed by the help of carboxyfluorescein
diacetate staining in the intestinal juice and bile salts. The percentages of viable bacteria
were evaluated on the basis of SSC vs. Fl-3 histograms for PI, and SSC vs. Fl-1 histograms
for cFDA.
Survival of EPS-producing L. reuteri at pH 2 and 2.5 of gastric fluid, in the intestinal
juice, in the presence of bile salts at concentrations 0.15, 0.2 and 0.3 %, and 5 M NaCl
solution was significantly higher in comparison with EPS non-producing L casei. EPS
production did not affect survival of strains at high temperatures, in the presence of very
high concentration of bile salts (0.5 %), even at extremely low pH of gastric juice (pH
1.5). The experiment results confirmed the protective effect of exopolysaccharides on
bacteria to adverse external conditions. Flow cytometry is suitable and reliable method
for assessment of bacterial viability in different conditions important for the selection
of probiotic bacteria, but appropriate fluorescent dyes must be used for different tests
since reactions between fluorochromes and used chemicals can occur.
Acknowledgement
This study was supported by the project of the Slovak Research and Development Agency
- APVV-0199-11 and the project VEGA 1/0834/12.
References
Nemcova R: Selection criteria of lactobacilli for probiotic use. - Vet Med Czech 42:19-27,
1997.
Bunthof C. J., van den Braak S., Breeuwer P., Rombouts F. M., Abee T. Rapid fluorescence
assessment of the viability of stressed Lactococcus lactis. - Appl Environ Microbiol 65:
3681-3689, 1999.
P48. NILE RED STAINING AND FLOW CYTOMETRY ANALYSIS OF
POLYHYDROXYBUTYRATE (PHB) ACCUMULATING BACTERIAL CELLS
Stanislav Obruca 1 , Dan Kucera 2 , Ivana Marova 1,2
1
Centre of Materials Research, Faculty of Chemistry, Brno University of Technology,
Brno, Czech Republic; e-mail: obruca@fch.vutbr.cz
2
Department of Food Chemistry and Biotechnology, Faculty of Chemistry, Brno
University of Technology, Brno, Czech Republic
Polyhydroxybutyrate (PHB) is polyesters accumulated by various bacteria in form of
intracellular granules which serve as a carbon and energy reserve material. Generally,
PHB is synthetized when carbon source is present in excess and bacteria cells are limited
by availability of nitrogen and/or phosphorous sources. Due to its mechanical and
144 Analytical Cytometry VII