Trimethylsilyl-sugar profiles of Streptococcus milleri and Streptococcus mitis

Seventy strains of 'viridans-group' streptococci were analysed gas chromatographically after preparation of trimethylsilyl ethers of their cellular sugars. The resulting profiles were evaluated as a possible aid to taxonomy. Glycerol, glucose, galactose, N-acetyl-glucosamine and N-acetylmuramic acid were found in all strains, in varying amounts. Rhamnose was the major neutral sugar in most strains, other than representatives of Streptococcus mitis , which invariably had ribose and usually anhydroribitol but no rhamnose. One strain of Strep, mitis possessed arabitol. Some strains of Strep. mitis and ' Strep. milleri ' were alone in containing N-acetylgalactosamine. A combination of N-acetylgalactosamine and rhamnose in the absence of ribose was diagnostic for strains of ' Strep. milleri '.     

Characterization of phage receptors in Streptococcus thermophilus using purified cell walls obtained by a simple protocol

A simple protocol was designed and applied to obtain Streptococcus thermophilus purified cell walls. To identify the structures involved in phage adsorption, the cell walls of two Strep. thermophilus strains were treated with sodium dodecyl sulphate and proteinase K. These treatments did not reduce the adsorption of phages CYM and 0BJ to the cell walls of Strep. thermophilus YSD10 and Strep. thermophilus BJ15, respectively. However, phage binding was reduced when the cell envelopes were treated with mutanolysin or trichloroacetic acid 5%, suggesting that the phage receptor component is part of the peptidoglycan or a polymer closely linked to it. The ability of several saccharides to inactivate both phages was also assayed. These phage inhibition experiments suggested that the phage CYM adsorbed to a component involving glucosamine and rhamnose, while glucosamine and ribose interfered with the adsorption of phage 0BJ.     

Taxonomic study of "tufted mitior" strains of streptococci (Streptococcus sanguinis biotype 11); recognition of a new genospecies

The taxonomic position of tufted strains of streptococci, phenotypically resembling Streptococcus mitis and previously referred to as 'tufted mitior' was investigated. By 16S rRNA sequence analysis, it was clear that the "tufted mitior" strains belonged to the mitis group of species within the genus Streptococcus. It was confirmed that these strains were taxonomically independent at the species level, sharing less than 43%, DNA-DNA similarity with all established species of the mitis group. However biochemical test data obtained, using three commercial identification kits (Rapid ID32 Strep, STREPTOGRAM, and Biolog GP-plate) together with in-house biochemical tests employing 4-MUF-linked fluorogenic substrates did not reveal sufficient differential tests with which to identify the "tufted mitior" strains unequivocally. From these data, we conclude that these "tufted mitior" strains represent a new taxon within the mitis group of the genus Streptococcus, and propose that they should be considered as a genospecies until differential phenotypic characteristics are found for their identification.     

Numerical taxonomy of Streptococcus

A numerical taxonomic study of strains of Streptococcus, together with representatives of allied genera, showed 28 reasonably distinct phenons. The major areas, with their phenons, were: (a) enterococcal species group (S. faecalis, S. faecium, 'S. avium' and a proposed new species 'S. gallinarum'); (b) paraviridans species group (S. bovis, S. equinus, S. salivarius, 'S. casseliflavus', S. mutans, S. raffinolactis and an unidentified Oral Group I); (c) lactic species group (S. lactis including S. cremoris); (d) thermophilic species group (S. thermophilus); (e) viridans species group (S. mitis, S. sanguis, a proposed new species 'S. oralis' and 'S. milleri'); (f) pyogenic species group (S. agalactiae, S. pyogenes, S. equi, 'S. equisimilis' including 'S. zooepidemicus, and a cluster of Lancefield Group B strains of human origin); (g) parapyogenic species group (S. uberis, 'S. dysgalactiae', and a cluster of strains of Lancefield Groups R, S and T). Species of Aerococcus, Gemella, Leuconostoc and Pediococcus are very closely related to the streptococci.     

A Selective Medium for the Enumeration of Streptococcus bovis by Membrane Filtration

A new selective medium (membrane-bovis agar) for the detection and enumeration of Streptococcus bovis is described. It has been successfully used to quantify this organism in polluted waters, sewage and faeces of humans and farm animals. This medium is based on the ability of Strep. bovis to utilize ammonium sulphate as its sole source of nitrogen. Streptococcus faecalis, Strep. faecium, Strep. equinus, Strep. salivarius. Strep. mitis and other bacteria commonly found in water, sewage and faeces are completely inhibited.
Streptococcus bovis appear to be the predominant faecal streptococci in the faeces of farm animals and absent in the faeces of humans. A total of 541 characteristic colonies (on m-BA), isolated from various sources were identified to species level. Over 97% proved to be Strep. bovis. Therefore, routine confirmatory tests on colonies growing on this medium would appear to be unnecessary.     

Physico-chemical and structural properties of the surfaces of Peptostreptococcus micros and Streptococcus mitis as compared to those of mutans streptococci, Streptococcus sanguis and Streptococcus salivarius.

The surface properties of nine Streptococcus mitis and four Peptostreptococcus micros strains from the oral cavity were examined and compared with a large group of oral streptococci. Zeta potential and contact angle measurements were employed to determine physico-chemical cell surface properties. In addition, elemental surface concentration ratios were obtained via X-ray photoelectron spectroscopy, and surface structures were examined with transmission electron microscopy. The S. mitis and P. micros strains were found to have higher isoelectric points, higher hydrophobicities and higher N/C surface concentration ratios than some other oral streptococci. The combined data suggest that both species possess large amounts of surface protein. All the S. mitis strains displayed abundant surface fibrils in negative staining, but the P. micros strains were devoid of surface appendages indicating that surface protein is present in different forms in the two species. The surfaces of S. mitis and P. micros type strains differed significantly from the other strains examined.     

Streptococcus bovis—an Approach to its Classification and its Importance as a Cause of Bovine Mastitis

Six streptococci isolated in high numbers from different mastitis samples have been identified as strains of Streptococcus bovis. The properties of the strains were compared with those strains of Strep, bovis from culture collections and also with those of two strains of Strep. mutans. Physiological properties, including ability to form capsules and dextran, the properties of the lactate dehydrogenases and hybridization between the deoxyribonucleic acid of the unknown strains and the reference strain of Strep. bovis were determined. It is concluded that Strep. bovis comprises strains with heterogeneous properties. No subgroups were apparent. The pathogenicity to the udder was determined for eight strains of Strep. bovis and one of Strep. mutans.     

新生儿颊粘膜定植菌株的拮抗性研究

本文分离在新生儿颊粘膜上皮细胞表面形成微菌落、且初代培养时菌落较纯的１５株ａ溶血细菌,进行对Ｂ链球菌、金黄色葡萄球菌、绿脓杆菌、大肠杆菌４种共７株菌的体外拮抗实验。１５株菌中包括８株ａＳｔｒｅｐ．,其中Ｓｔｒｅｐ．ｍｉｔｉｓ４株,Ｓｔｒｅｐ．ｏｒａｌｉｓ２株、Ｓｔｒｅｐ．Ｓａｌｉｖ．Ｓａｌｉｖａｒｉｕｓ１株、Ｓｔｒｅｐ．ｉｎｔｅｒｍｅｄｉｕｓ１株;ＬＣ．ｌａｃｔｉｓ．ｃｒｅｍｏｒｉｓ５株、Ｇｅｍｅｌａｍｏｒｂｉｌｏｒｕｍ１株、Ｇｅｍｅｌａｈａｅｍｏｌｙｓａｎｓ１株。结果约６０％（９／１５）的颊粘膜定植株对两株及两株以上的病原菌株或阴性杆菌株有拮抗作用,只对１株菌有损坏抗作用的ａ溶血菌４株,完全无拮抗作用的菌株２株;ａＳｔｒｅｐ．、ＬＣ．ｌａｃｔｉｓ．ｃｒｅｍｏｒｉｓ的拮抗作用较强;拮抗作用的有无、强弱有很强的菌株特异性     

Role of Bacteriocin During Plaque Formation by Streptococcus salivarius and Streptococcus sanguis on a Tooth in an Artificial Mouth

Bacteriocinogenic strains of Streptococcus salivarius antagonized Strep. sanguis on blood agar and in Todd-Hewitt broth with, but not without, sucrose. Each organism produced plaque in vitro but, after a mixed inoculum with both organisms, the numbers of Strep. sanguis rapidly fell to <0.01% plaque organisms. A non-bacterio-cinogenic mutant of Strep. salivarius was itself inhibited by Strep. sanguis in the plaque-producing system; derivatives of Strep. sanguis partially resistant to bacteriocin in the plate test nevertheless failed to co-habit plaque with bacteriocinogenic Strep. salivarius. The latter could suppress Strep. sanguis in established monoculture plaque but only if sucrose were continuously supplied. It was concluded that the effect of bacteriocin in plaque formation by these streptococci is linked to other as yet unknown properties which may account for the absence of Strep. salivarius from plaque in vivo .     

Identification of Streptococcus salivarius by PCR and DNA probe

AIMS: To establish species-specific PCR and DNA probe methods for Streptococcus salivarius and to clarify the distribution of dextranase in oral isolates of Strep. salivarius. METHODS AND RESULTS: A pair of PCR primers and a DNA probe were designed based on the nucleotide sequence of the dextranase gene of Strep. salivarius JCM5707. Both the PCR primer and the DNA probe specifically detected Strep. salivarius but none of the other oral streptococci (23 strains of 13 species). The primer and the probe were capable of detecting 1 pg and 1 ng of the genomic DNA, respectively, purified from Strep. salivarius JCM5707. All oral isolates (130 strains from 12 subjects) of Strep. salivarius from human saliva were positive by both methods. CONCLUSION: The present PCR and DNA probe methods are highly specific to Strep. salivarius and are useful for the its detection and identification of this bacterium. The dextranase widely distributes among oral isolates of Strep. salivarius. Significance and Impact of the Study: The DNA sequence of a dextranase gene present in the genome of Strep. salivarius is useful as the target DNA of the species-specific PCR and DNA probe.     

Inhibitory activity of Streptococcus mitis against oral bacteria

The antagonistic properties of three strains of Streptococcus mitis were investigated. They were found to inhibit a wide range of oral bacteria; Gram-positive and Gram-negative, facultative and anaerobic species being susceptible. The S. mitis strains were shown to be producing hydrogen peroxide, this being partially responsible for the aerobic inhibitory activity. A second inhibitory factor(s) was also produced, aerobically and anaerobically, although this could not be isolated. A limited characterization of this factor was undertaken using plate cultures.     

Distribution and Properties of Serological Types of Streptococcus faecium, Streptococcus durans and Related Strains

S ummary . The distribution of 19 serological types of Streptococcus faecium and related organisms has been studied, using 367 strains isolated mainly from faecal samples. Several types occurred in man as well as in pigs, sheep, cattle or chickens.
Strains of the same serological type showed a diversity of fermentation reactions, so that organisms which could be identified as Streptococcus durans shared a common type antigen with Strep. faecium strains. The evidence given here supports the proposal that Strep. durans should in future be considered as a variant of Strep. faecium .
It has also been shown that, in common with those of Streptococcus faecalis , the type antigens of the Strep. faecium types are cell wall components.     

Lactose Hydrolysing Enzymes in Streptococcus lactis and Streptococcus cremoris and also in some other Species of Streptococci

Two types of Streptococcus lactis could be identified: cheese starter strains, which contain β-phosphogalactosidase and ferment lactose rapidly to lactate, and non-dairy strains, which contain both β-galactosidase and β-phosphogalactosidase and ferment lactose slowly to a variety of end products. All strains had homolactic glucose fermentations and heterolactic galactose fermentations. Other species of streptococci were examined for lactose hydrolysing enzymes and found to contain β-phosphogalactosidase, except Strep, thermophilus and Strep. faecium which had high levels of β-galactosidase. Discrepancies were found in the lactose hydrolysing enzymes content when the cells were treated in different ways.     

Inhibition of Streptococcus mutans NS adhesion to glass with and without a salivary conditioning film by biosurfactant- releasing Streptococcus mitis strains

The release of biosurfactants by adhering microorganisms as a defense mechanism against other colonizing strains on the same substratum surface has been described previously for probiotic bacteria in the urogenital tract, the intestines, and the oropharynx but not for microorganisms in the oral cavity. Two Streptococcus mitis strains (BA and BMS) released maximal amounts of biosurfactants when they were grown in the presence of sucrose and were harvested in the early stationary phase. The S. mitis biosurfactants reduced the surface tensions of aqueous solutions to about 30 to 40 mJ m(-2). Biochemical and physicochemical analyses revealed that the biosurfactants released were glycolipids. An acid-precipitated fraction was extremely surfactive and was identified as a rhamnolipidlike compound. In a parallel-plate flow chamber, the number of Streptococcus mutans NS cells adhering to glass with and without a salivary conditioning film in the presence of biosurfactant-releasing S. mitis BA and BMS (surface coverage, 1 to 4%) was significantly reduced compared with the number of S. mutans NS cells adhering to glass in the absence of S. mitis. S. mutans NS adhesion in the presence of non-biosurfactant-releasing S. mitis BA and BMS was not reduced at all. In addition, preadsorption of isolated S. mitis biosurfactants to glass drastically reduced the adhesion of S. mutans NS cells and the strength of their bonds to glass, as shown by the increased percentage of S. mutans NS cells detached by the passage of air bubbles through the flow chamber. Preadsorption of the acid-precipitated fraction inhibited S. mutans adhesion up to 80% in a dose-responsive manner. These observations indicate that S. mitis plays a protective role in the oral cavity and protects against colonization of saliva-coated surfaces by cariogenic S. mutans.     

Deoxyribonuclease activity in Streptococcus bovis

Deoxyribonuclease activity was tested with lambda bacteriophage DNA as a substrate in three Streptococcus bovis strains isolated from the rumen of sheep and cow. Non-specific nuclease activity was detected in the cell extract of Strep, bovis BM 114. Specific endonuclease activity was detected in the cell extract of the strain Strep. bovis II/I, isolated from the rumen of a sheep. A rapid technique is proposed for the detection of endonuclease activity of rumen bacteria.     

Plaque Formation by Streptococci in an Artificial Mouth and Factors Influencing Colonization

The plaque-producing properties of Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans, Streptococcus mitis and Streptococcus faecalis were investigated in an artificial mouth with continuous supply of nutrient. Attention was focused on the role of salivary factors and sucrose in tooth colonization. Plaque formation by single cultures depended on the ability to produce tenacious extracellular polysaccharide or to cohabit the tooth with an organism having this property. Sucrose was the only essential additive to nutrient broth necessary for plaque formation and could not be substituted by sterile natural saliva. Saliva neither facilitated colonization by Strep. mitis nor prevented colonization by Strep. salivarius as may have been supposed from previous reports.     

Complete structure of the cell surface polysaccharide of Streptococcus oralis C104: a 600-MHz NMR study

Specific lectin-carbohydrate interactions between certain oral streptococci and actinomyces contribute to the microbial colonization of teeth. The receptor molecules of Streptococcus oralis, 34, ATCC 10557, and Streptococcus mitis J22 for the galactose and N-acetylgalactosamine reactive fimbrial lectins of Actinomyces viscosus and Actinomyces naeslundii are antigenically distinct polysaccharides, each formed by a different phosphodiester-linked oligosaccharide repeating unit. These streptococci all coaggregated strongly with both A. viscosus and A. naesludii strains, whereas S. oralis C104 interacted preferentially with certain strains of the latter species. Receptor polysaccharide was isolated from S. oralis C104 cells and was shown to contain galactose, N-acetylgalactosamine, ribitol, and phosphate with molar ratios of 4:1:1:1. The 1H NMR spectrum of the polysaccharide shows that it contains a repeating structure. The individual sugars in the repeating unit were identified by 1H coupling constants observed in E-COSY and DQF-COSY spectra. NMR methods included complete resonance assignments (1H and 13C) by various homonuclear and heteronuclear correlation experiments that utilize scalar couplings. Sequence and linkage assignments were obtained from the heteronuclear multiple-bond correlation (HMBC) spectrum. This analysis shows that the receptor polysaccharide of S. oralis C104 is a ribitol teichoic acid polymer composed of a linear hexasaccharide repeating unit containing two residues each of galactopyranose and galactofuranose and a residue each of GalNAc and ribitol joined end to end by phosphodiester linkages with the following structure. [----6)Galf(beta 1----3)Galp(beta 1----6)Galf(beta 1----6)GalpNAc(beta 1----3) Galp(alpha 1----1)ribitol(5----PO4-]n     

Production by and isolation of exopolysaccharides from Streptococcus thermophilus grown in a milk medium and evidence for their growth-associated biosynthesis

Four Streptococcus thermophilus strains ( Strep. thermophilus BTC, Strep. thermophilus LY03, Strep. thermophilus 480 and Strep. thermophilus Sfi20) have been examined for their exopolysaccharide production capacity. All strains produced a polymer composed of the neutral sugars glucose and galactose, but in different ratios. It was clearly shown that the biosynthesis of exopolysaccharides from Strep. thermophilus LY03 is growth-associated and hence displays primary metabolite kinetics. The monomer ratio of the exopolysaccharide synthesized did not vary throughout the fermentation cycle. The production kinetics and exopolysaccharide yields were strongly dependent on the fermentation conditions. Physical factors such as temperature, pH and oxygen tension as well as chemical factors (medium composition, initial lactose concentration, carbon/nitrogen levels) were of utmost importance.     

Presence of additional peptidases in Streptococcus thermophilus CNRZ 302 compared to Lactococcus lactis

Streptococcus thermophilus is widely used in the dairy industry but little is known about its peptidase system. The aim of this study was to determine the biochemical and genetic characteristics of this system, and to compare it to the well known system of Lactococcus lactis . We separated the intracellular proteins of Strep. thermophilus CNRZ 302 and L. lactis NCDO 763 by ion-exchange chromatography and we detected the activity of the different types of peptidases. In both L. lactis and Strep. thermophilus strains, we showed 13 different peptidase activities with biochemical homologies between both species. Streptococcus thermophilus also possessed two peptidases which we did not find in L. lactis : an aminopeptidase and an oligopeptidase. We performed Southern blot experiments and among the eight peptidase genes tested, only the genes encoding the general aminopeptidases, pepC and pepN , were homologous between the L. lactis and Strep. thermophilus strains. Besides biochemical and genetic similarities, the peptidase systems of Strep. thermophilus and L. lactis thus differed by the presence of additional peptidases in Strep. thermophilus .