title: Characterisation of probiotic properties in human vaginal lactobacilli strains.
abstract: BACKGROUND
  Vaginal lactobacilli offer protection against recurrent urinary infections, bacterial vaginosis, and vaginal candidiasis.
  
  
  OBJECTIVE
  To characterise the isolated vaginal lactobacilli strains for their probiotic properties and to compare their probiotic potential.
  
  
  METHODS
  The Lactobacillus strains were isolated from vaginal samples by conventional culturing and identified by sequencing of the 16S rDNA fragment. Several functional properties were detected (production of hydrogen peroxide and lactic acid; antagonistic activity against Escherichia coli, Candida albicans, Candida glabrata, and Gardnerella vaginalis; auto-aggregation and adhesiveness) as well as safety (haemolytic activity, antibiotic susceptibility, presence of transferrable resistance genes).
  
  
  RESULTS
  A total of 135 vaginal lactobacilli strains of three species, Lactobacillus crispatus (56%), Lactobacillus jensenii (26%), and Lactobacillus gasseri (18%) were characterised using several functional and safety tests. Most of L. crispatus (89%) and L. jensenii (86%) strains produced H2O2. The best lactic acid producers were L. gasseri (18.2±2.2 mg/ml) compared to L. crispatus (15.6±2.8 mg/ml) and L. jensenii (11.6±2.6 mg/ml) (p<0.0001; p<0.0001, respectively). L. crispatus strains showed significantly higher anti-E. coli activity compared to L. jensenii. L. gasseri strains expressed significantly lower anticandidal activity compared to L. crispatus and L. jensenii (p<0.0001). There was no significant difference between the species in antagonistic activity against G. vaginalis. Nearly a third of the strains were able to auto-aggregate while all the tested strains showed a good ability to adhere to HeLa cells. None of the tested lactobacilli caused haemolysis. Although phenotypical resistance was not found to ampicillin, chloramphenicol, erythromycin, gentamycin, tetracycline, and vancomycin, the erm(B), tet(M), and tet(K) were detected in some strains. All strains were resistant to metronidazole, trimethoprim/sulfamethoxazole, and kanamycin.
  
  
  CONCLUSIONS
  Our study revealed that the production of different antimicrobial metabolites is highly strain-specific and that the metabolites are not correlated with each other. L. crispatus displays better antagonistic activity against E. coli and Candida spp. than L. gasseri and L. jensenii; therefore; a potential probiotic candidate could be found among L. crispatus strains.
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Pirje
authors.initials: P
authors.lastname: Hütt
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Eleri
authors.initials: E
authors.lastname: Lapp
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Štšepetova
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Imbi
authors.initials: I
authors.lastname: Smidt
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Heleri
authors.initials: H
authors.lastname: Taelma
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Natalja
authors.initials: N
authors.lastname: Borovkova
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Helen
authors.initials: H
authors.lastname: Oopkaup
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Ave
authors.initials: A
authors.lastname: Ahelik
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Tiiu
authors.initials: T
authors.lastname: Rööp
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Hoidmets
authors.affiliation: Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Külli
authors.initials: K
authors.lastname: Samuel
authors.affiliation: Competence Centre on Health Technologies, Tartu, Estonia.
authors.forename: Andres
authors.initials: A
authors.lastname: Salumets
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.|Competence Centre on Health Technologies, Tartu, Estonia; reet.mandar@ut.ee.
authors.forename: Reet
authors.initials: R
authors.lastname: Mändar
keywords: Lactobacillus crispatus; Lactobacillus gasseri; Lactobacillus jensenii; probiotic; vaginal lactobacilli