Fadime Kiran

Evaluation of in vitro Probiotic Potential of Pediococcus pentosaceus OZF Isolated from Human Breast Milk

This study was conducted to evaluate the probiotic properties of Pediococcus pentosaceus OZF isolated from human breast milk. The results obtained so far suggest that the strain is resistant to low pH, bile salt, pepsin and pancreatin, so it could survive while passing through the upper part of the gastrointestinal tract and reveal its potential probiotic action on host organism. The strain was non-pathogenic (γ-hemolytic), produced anti-Listerial bacteriocin, exhibited a strong autoaggregating phenotype (85.71%) and demonstrated 6.26 and 12.99% coaggregation with Salmonella enterica serotype Typhimurium SL 1344 and Escherichia coli LMG 3083 (ETEC), respectively. The degree of adhesion of Ped. pentosaceus OZF to the human Caco-2 cell line was investigated and when compared to the adhesion of pathogenic strains tested, it was shown to inhibit the growth of human enterotoxigenic E. coli LMG 3083 (ETEC) and of Salm. Typhimurium SL 1344. Ped. pentosaceus OZF seems to adhere to human intestinal cells via mechanisms that involve different combinations of carbohydrate and lipid factors on the bacteria and eukaryotic cell surface. The percentage of adhesion to n-hexadecane was 34% showing that the surface was rather hydrophilic. Higher affinity displayed by Ped. pentosaceus OZF for chloroform demonstrates the basic property of a cell, which may be due to the presence of carboxylic groups on the cell surface.

Immunomodulatory function and in vivo properties of Pediococcus pentosaceus OZF, a promising probiotic strain

Some of the important properties of probiotics are the ability to survive during gastrointestinal transit and to modulate the immune functions. The objectives of the reported study were to assess in vivo gastrointestinal survival of orally administered Pediococcus pentosaceus OZF using an animal model BALB/c mice, and to examine its effects on the immune response. Following oral administration to mice, the ability of Pediococcus pentosaceus OZF to pass and survive through the mouse gastrointestinal system was investigated by analyzing the recovery of the strain in fecal samples. Microbiological and polymerase chain reaction (PCR) methods proved that the strain OZF could overcome specific conditions in the gastrointestinal tract of mice and reach the intestine alive after ingestion. To observe the effect of oral administration on immune response, IL-6, IL-12 and IFN-γ were measured by ELISA, and the strain OZF was found to cause increases in IL-6 synthesis in regularly fed mice. However, stimulation was carried out with various concentrations of bacterial ssDNA and heat killed cells of Pediococcus pentosaceus OZF. The heat killed cells of the strain OZF were shown to produce IFN-γ independently from IL-12. On the other hand, a significant difference between control and experimental group was noticed when lipopolysaccharide, a TLR4 (toll like receptor) ligand, was used. Overall, Pediococcus pentosaceus OZF may be a valuable probiotic strain for therapeutic uses. Nevertheless, further studies on the mechanisms of immunomodulatory effect will allow for better clarification of the immune functions of this strain.

Evidence for a chromosomally determined mesenterocin, a bacteriocin produced by Leuconostoc mesenteroides subsp. mesenteroides OZ

Mesenterocin, a small anti‐listerial peptide of 3.5 kDa produced by Leuconostoc mesenteroides subsp. mesenteroides OZ at the end of exponential growth was inactivated by proteolytic enymes, stable to cold storage (4 °C for 3 d), heat, organic solvents and surfactants, and exhibited maximum bactericidal mode of activity in the pH range 3 to 10. Although Leu. mesenteroides subsp. mesenteroides OZ harboured plasmids ranging in size from 3.6 to 9.7 kbp, no evidence was obtained indicating that mesenterocin was under the control of extrachromosomal plasmids because loss of bacteriocin production following plasmid curing experiments could not be correlated with plasmid loss and the lack of detectable plasmids suggested a chromosomal location for the genetic determinants of mesenterocin. To determine its chromosomal location, genetic determinants of the bacteriocin of Leu. mesenteroides subsp. mesenteroides OZ were tested with previously described bacteriocins of the Leuconostocs through PCR and results of PCR indicated that the gene for mesenterocin activity is located on the chromosome. No papers have been published, to the best of our knowledge, on chromosomal location of bacteriocin of Leuconostoc species. Association of meat spoilage with bacteriocin producing heterofermentative Leu. mesenteroides subsp. mesenteroides OZ is also suggested. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)