Lactobacillus gasseri K7 is a probiotic strain that produces bacteriocins gassericin K7 A and K7 B. In order to develop a real-time quantitative PCR assay for the detection of L. gasseri K7, 18 reference strains of the Lactobacillus acidophilus group and 45 faecal samples of adults who have never consumed strain K7 were tested with PCR using 14 pairs of primers specific for gassericin K7 A and K7 B gene determinants. Incomplete gassericin K7 A or K7 B gene clusters were found to be dispersed in different lactobacilli strains as well as in faecal microbiota. One pair of primers was found to be specific for the total gene cluster of gassericin K7A and one for gassericin K7B. The real-time PCR analysis of faecal samples spiked with K7 strain revealed that primers specific for the gene cluster of the gassericin K7 A were more suitable for quantitative determination than those for gassericin K7 B, due to the lower detection level. Targeting of the gassericin K7 A or K7 B gene cluster with specific primers could be used for detection and quantification of L. gasseri K7 in human faecal samples without prior cultivation. The results of this study also present new insights into the prevalence of bacteriocin-encoding genes in gastrointestinal tract.

• MeSH
• Bacteriocins genetics   MeSH
• Bacteriological Techniques methods   MeSH
• DNA Primers genetics   MeSH
• Adult MeSH
• Feces microbiology   MeSH
• Real-Time Polymerase Chain Reaction methods   MeSH
• Lactobacillus acidophilus genetics   isolation & purification   MeSH
• Humans MeSH
• Sensitivity and Specificity MeSH
• Healthy Volunteers MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Bacteriocins MeSH
• DNA Primers MeSH

Eleven strains of Lactobacillus collected in the Culture Collection of Dairy Microorganisms (CCDM) were evaluated for selected probiotic properties such as survival in gastrointestinal fluids, antimicrobial activity, and competition with non-toxigenic Escherichia coli O157:H7 for adhesion on Caco-2 cells. The viable count of lactobacilli was reduced during 3-h incubation in gastric fluid followed by 3-h incubation in intestinal fluid. All strains showed antimicrobial activity and the three most effective strains inhibited the growth of at least 16 indicator strains. Antimicrobial metabolites of seven strains active against Lactobacillus and Clostridium indicator strains were found to be sensitive to proteinase K and trypsin, which indicates their proteinaceous nature. The degree of competitive inhibition of non-toxigenic E. coli O157:H7 adhesion on the surface of Caco-2 cells was strain-dependent. A significant decrease (P < 0.05) in the number of non-toxigenic E. coli O157:H7 adhering to Caco-2 cells was observed with all lactobacilli. Three strains were selected for additional studies of antimicrobial activity, i.e., Lactobacillus gasseri CCDM 215, Lactobacillus acidophilus CCDM 149, and Lactobacillus helveticus CCDM 82.

• MeSH
• Antibiosis * MeSH
• Anti-Infective Agents metabolism   MeSH
• Bacterial Adhesion MeSH
• Caco-2 Cells MeSH
• Epithelial Cells microbiology   MeSH
• Escherichia coli O157 physiology   MeSH
• Lactobacillus growth & development   physiology   MeSH
• Humans MeSH
• Microbial Viability drug effects   MeSH
• Probiotics pharmacology   MeSH
• Gastric Juice microbiology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Infective Agents MeSH

Five samples of Airag and 20 of Tarag (both in Mongolia) were collected from scattered households. One hundred strains of lactic acid bacteria (LAB) were isolated and identified from these samples according to phenotypic characterization and 16S rRNA gene sequence analysis. Eighty-five isolates belonged to the genus Lactobacillus, 15 being classified as coccoid LAB. All isolates belonged to 5 genera and 11 to different species and subspecies. Lactobacillus (Lb.) helveticus was predominant population in Airag samples, Lb. fermentum and Lb. helveticus were the major LAB microflora in Tarag.

• MeSH
• Bacteria classification   isolation & purification   metabolism   MeSH
• DNA, Bacterial chemistry   genetics   MeSH
• Phylogeny MeSH
• Lactic Acid metabolism   MeSH
• Milk microbiology   MeSH
• Molecular Sequence Data MeSH
• DNA, Ribosomal chemistry   genetics   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Sequence Analysis, DNA MeSH
• Cluster Analysis MeSH
• Bacterial Typing Techniques MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Mongolia MeSH
• Names of Substances
• DNA, Bacterial MeSH
• Lactic Acid MeSH
• DNA, Ribosomal MeSH
• RNA, Ribosomal, 16S MeSH