Aims: Lactobacilli are widely distributed in food and the environment, and some colonize the human body as commensal bacteria. The aim of this study was to determine the species of lactobacilli that colonize the vagina and compare them with those found in food and the environment. Methods and Results: Thirty‐five Lactobacillus strains from women from seven countries were isolated, and sequences from 16S rRNA genes were determined and compared with existing data in GenBank. A phylogenetic tree was achieved using the Neighbour‐Joining method based on the analysis of 1465 nucleotides. The results showed that most vaginal isolates were L. crispatus, L. jensenii and L. gasseri. Some were L. vaginalis, L. fermentum, L. mucosae, L. paracasei and L. rhamnosus. Two isolates from a native American woman displayed distinct branches, indicating novel phylotypes. Few vaginal isolates matched food or environmental Lactobacillus species. Conclusions: Most women worldwide were colonized by three common Lactobacillus species: L. crispatus, L. jensenii and L. gasseri. Significance and Impact of Study: Knowledge of vaginal Lactobacillus species richness and distribution in women worldwide may lead to the design of better probiotic products as bacterial replacement therapy.

SummaryDental plaque biofilm formation proceeds through a developmental pathway initiated by the attachment of pioneer organisms, such as Streptococcus gordonii, to tooth surfaces. Through a variety of synergistic interactions, pioneer organisms facilitate the colonization of later arrivals including Porphyromonas gingivalis , a potential periodontal pathogen. We have investigated genes of S. gordonii required to support a heterotypic biofilm community with P. gingivalis . By screening a plasmid integration library of S. gordonii, genes were identified that are crucial for the accumulation of planktonic P. gingivalis cells into a multispecies biofilm. These genes were further investigated by specific mutation and complementation analyses. The biofilm-associated genes can be grouped into broad categories based on putative function as follows: (i) intercellular or intracellular signalling ( cbe and spxB ), (ii) cell wall integrity and maintenance of adhesive proteins ( murE, msrA and atf ), (iii) extracellular capsule biosynthesis ( pgsA and atf ), and (iv) physiology ( gdhA, ccmA and ntpB ). In addition, a gene for a hypothetical protein was identified. Biofilm visualization and quantification by confocal microscopy confirmed the role of these genes in the maturation of the multispecies community, including biofilm architectural development. The results suggest that S. gordonii governs the development of heterotypic oral biofilms through multiple genetic pathways.

that the conjugative transfer of all these elements shares a common mechanism, as the elements are derived from an ancestral element with transfer properties.Tn5253, formerly called the fl(cat tet) element (36), was originally detected as a heterologous insertion in the chromosome of the plasmid-free clinical isolate S. pneumoniae BM6001 (3, 9). By inserting the Escherichia coli vector plasmid pVA891 (22) (which is incapable of autonomous replication in streptococci) at many sites specifically within Tn5253, we were able to clone and recover parts of the element in E. coli (37). Physical analysis of the passenger DNAs from these plasmids made it possible to construct a detailed restriction map of this 65.5-kb element, to localize the drug resistance determinants, and to identify its junction and target regions in the pneumococcal chromosome (36), (Fig. 1)

Lactobacilli play an important role in maintaining vaginal health. However, during bacterial vaginosis lactobacilli decrease for unknown reasons. Our preliminary study showed that phages could infect vaginal lactobacilli. Therefore, the aim of this study was to analyze the distribution, virulence, and types of vaginal Lactobacillus phages isolated from women of two countries: the United States and Turkey. A total of 209 vaginal lactobacilli were isolated from reproductive-aged women in the United States (n ‫؍‬ 107) and Turkey (n ‫؍‬ 102). By analysis of 16S rRNA gene sequence and by comparison of protein profiles, most lactobacilli were identified as L. crispatus, L. gasseri, and L. jensenii. After mitomycin C induction, 28% of American lactobacilli and 36% of Turkish lactobacilli released phages. A total of 67 phages were isolated and further characterized by their host range, electron microscopy, and DNA homology. All 67 phages were infective against lactobacilli from both collections. The host ranges of most phages were broad, including multiple Lactobacillus species. Even though the phages were all temperate, they were able to cause lytic infection in various strains. The electron micrographs of these phages showed a hexagon-shaped head and a long tail with or without a contractile tail sheath. Based on their morphology, these phages belonged to Bradley's phage groups A and B, and could be further classified into four morphotypes. All four types were found among American phages, but only three were found among Turkish isolates. DNA hybridization with labeled probes of the four types of phages revealed that additional genetic types existed within each morphotype among these phages. The phage genomic sizes ranged between 34 and 55 kb. Many of the lysogenic Lactobacillus strains released phages spontaneously at a high frequency of 10 ؊3 to 10 ؊4 PFU/cell. In conclusion, lysogeny in vaginal lactobacilli is widely spread. Some lysogenic lactobacilli spontaneously release phages with a broad host range, which can be lytic against other vaginal lactobacilli regardless of their geographic origin.Lactobacilli indigenous to the human vagina are beneficial to women's health (35). These bacteria can inhibit other potentially harmful microorganisms by producing lactic acid, hydrogen peroxide (H 2 O 2 ), and antimicrobial substances (12,23,43). In most healthy women, lactobacilli are the dominant species in the vagina. Theoretically, the anaerobic bacteria are suppressed by lactobacilli (12, 23) and cannot replace lactobacilli unless the latter is first diminished. However, the group of anaerobic bacteria commonly outnumber lactobacilli, causing a microbial imbalance called bacterial vaginosis (BV) (3,9,10,15,38,40).BV is a clinical condition that is characterized by decreased lactobacilli and an increased number of anaerobic gram-negative rods, Gardnerella species, and genital mycoplasmas (10,38,40). Women who suffer from BV may have an increased discharge that often has an unpleasant fishy odor. BV has been associated w...

Streptococcus gordonii genes involved in beta-glucoside metabolism are induced in vivo on infected heart valves during experimental endocarditis and in vitro during biofilm formation on saliva-coated hydroxyapatite (sHA). To determine the roles of beta-glucoside metabolism systems in biofilm formation, the loci of these induced genes were analyzed. To confirm the function of genes in each locus, strains were constructed with gene inactivation, deletion, and/or reporter gene fusions. Four novel systems responsible for beta-glucoside metabolism were identified, including three phosphoenolpyruvate-dependent phosphotransferase systems (PTS) and a binding protein-dependent sugar uptake system for metabolizing multiple sugars, including beta-glucosides. Utilization of arbutin and esculin, aryl-beta-glucosides, was defective in some mutants. Esculin and oligochitosaccharides induced genes in one of the three beta-glucoside metabolism PTS and in four other genetic loci. Mutation of genes in any of the four systems affected in vitro adhesion to sHA, biofilm formation on plastic surfaces, and/or growth rate in liquid medium. Therefore, genes associated with beta-glucoside metabolism may regulate S. gordonii in vitro adhesion, biofilm formation, growth, and in vivo colonization.Streptococcus gordonii is a pioneer colonizer on the surface of human teeth, initiating the formation of dental plaque (25).Although not directly associated with dental or gingival diseases in the oral cavity, S. gordonii colonizes damaged heart valves once it enters the bloodstream in the experimental rabbit (15) and is considered to cause endocarditis in humans (1,8,12). Thus, the virulence of S. gordonii is reflected in its ability to adhere, colonize, and survive in the heart, where it is a pathogen, and on teeth in the oral cavity, where it is not. Its virulence in a specific environment may reflect expression of genes uniquely in that environment.Using an in vivo expression technology (IVET) library constructed in S. gordonii V288, at least 13 genes were shown to be expressed in vivo on infected heart valves during experimental endocarditis, but they were unexpressed in vitro under laboratory conditions (15). Since expression occurred only on heart valves, these genes were suggested to contribute to virulence and perhaps pathogenicity. Similarly, S. gordonii genes expressed during in vitro colonization of saliva-coated hydroxyapatite (sHA) were identified using the IVET library (17). Among the genes expressed during colonization of sHA and damaged heart valves in the rabbit were beta-glucoside metabolism-encoding genes. We therefore initiated in vitro studies to understand how the beta-glucoside metabolism genes might contribute to colonization of heart valves in infective endocarditis and on sHA.Bacteria ferment beta-glucoside sugar substrates, including cellobiose, arbutin, salicin, and esculin. While common in plants and useful in establishing phenotypic fermentation patterns of bacteria, the aryl-beta-disaccharides are not found in mammali...

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CbpA was suggested to contribute to site 2 interactions in our two-site model of platelet aggregation in response to S. sanguis. Platelet polymorphisms were suggested to contribute to the thrombogenic potential of S. sanguis.