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PubMed1980

Agglutination of human erythrocytes by Fusobacterium nucleatum: factors influencing hemagglutination and some characteristics of the agglutinin.

Various aspects of agglutination of human erythrocytes by fusobacterium nucleatum were examined. Titration experiments done in buffered saline at pH 6 to 10 showed the same agglutination endpoint. The presence of high concentrations of NaCl in reaction mixtures did not alter titers, but KCl in concentrations of 0.5 to 3.6 M increased titers twofold. The agglutinin was inactivated by heat, acid, alkali, 5% Formalin, and the proteolytic enzyme subtilopeptidase A and therefore appeared to be a protein. Treatment of bacterial cells with 2-mercaptoethanol had no effect. Hemagglutination inhibition experiments revealed that arginine and other compounds containing a guanido group as part of their structure were inhibitory at low concentrations. Various hexoses, some hexose derivatives, and most common metal ions, when added to bacterium-erythrocyte mixtures, had no effect. The binding of dansyl-L-arginine to bacteria, but not erythrocytes, was demonstrable by ultraviolet fluorescence microscopy.

Agglutinins↗

PubMed1982

Pathway of lysine degradation in Fusobacterium nucleatum.

Lysine was fermented by Fusobacterium nucleatum ATCC 25586 with the formation of about 1 mol each of acetate and butyrate. By the use of [1-14C]lysine or [6-14C]lysine, acetate and butyrate were shown to be derived from both ends of lysine, with acetate being formed preferentially from carbon atoms 1 and 2 and butyrate being formed preferentially from carbon atoms 3 to 6. This indicates that the lysine carbon chain is cleaved between both carbon atoms 2 and 3 and carbon atoms 4 and 5, with the former predominating [1-14C]acetate was also extensively incorporated into butyrate, preferentially into carbon atoms 3 and 4. Cell-free extracts of F. nucleatum were shown to catalyze the reactions of the 3-keto,5-aminohexanoate pathway of lysine degradation, previously described in lysine-fermenting clostridia. The 3-keto,5-aminohexanoate cleavage enzyme was partially purified and shown to have properties much like those of the clostridial enzyme. We conclude that both the pathway and the enzymes of lysine degradation are similar in F. nucleatum and lysine-fermenting clostridia.

Acetates↗

PubMed1982

Extraction and properties of hemagglutinin from cell wall fragments of Fusobacterium nucleatum.

To study the hemagglutinin of Fusobacterium nucleatum, methods were sought to solubilize and purify this component. When cells of F. nucleatum were ruptured by passage through a French press, the fragments lost virtually all ability to agglutinate human erythrocytes. Extraction of the fragments with 2% Triton X-100 for 30 min at 22 degrees C restored hemagglutinating activity (HA). Hemagglutination by these fragments could be inhibited by arginine, as can hemagglutination by intact bacteria. Treatment of active cell wall fragments with pronase and 2% Triton X-100-EDTA at 37 degrees C or with pronase and 0.1% Triton X-100-EDTA at pH 10.0 allowed recovery of solubilized HA. The former HA was inhibited by arginine (arg+) whereas the latter was not (arg-). Fractionation of the arg+ extract by preparative isoelectric focusing showed that HA was recovered from the gel sections having a pH between 4.5 and 5.5. Hemagglutination by this preparation was still arg+. Chromatography of this hemagglutinin on DEAE-Sephadex increased the specific activity to high levels with a loss of inhibition by arginine. A fraction from the DEAE-Sephadex column containing 10,700 HA units per mg of protein was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Solubilization at 22 degrees C before electrophoresis revealed three Coomassie blue-staining bands which migrated with apparent molecular weights of about 21,000, 38,000 and 60,000. When the same DEAE fraction was boiled in sodium dodecyl sulfate, electrophoresis revealed only one band with an apparent molecular weight of 21,000.

Arginine↗

PubMed1987

Amino acid-dependent transport of sugars by Fusobacterium nucleatum ATCC 10953.

Resting cells of Fusobacterium nucleatum 10953 (grown previously in a medium containing glucose) failed to accumulate glucose under aerobic or anaerobic conditions. However, the addition of glutamic acid, lysine, or histidine to anaerobic suspensions of cells caused the immediate and rapid accumulation of glucose. Except for the amino acid-dependent transport of galactose and fructose (the latter being transported at approximately one-third the rate of glucose), no other sugars tested were accumulated by the resting cells. Amino acid-dependent uptake of sugar(s) by F. nucleatum was abolished by exposure of cells to air, and under aerobic conditions the rates of fermentation of glutamic acid and lysine were less than 15% of the rates determined anaerobically. The energy necessary for active transport of the sugars (acetyl phosphate and ATP) is derived from the anaerobic fermentation of glutamic acid, lysine, or histidine. Competition studies revealed that glucose and galactose were mutual and exclusive inhibitors of transport, and it is suggested that the two sugars (Km = 14 microM) are translocated via a common carrier. The products of amino acid-dependent sugar transport were recovered from resting cells as ethanol-precipitable, high-molecular-weight polymers. Polymer formation by F. nucleatum, during growth in medium containing glucose or galactose, was confirmed by electron microscopy.

Aerobiosis↗

PubMed1990

Regulation of fructose metabolism and polymer synthesis by Fusobacterium nucleatum ATCC 10953.

Energy for the anaerobic growth of Fusobacterium nucleatum ATCC 10953 can be derived from the fermentation of sugar (fructose) or amino acid (glutamate). During growth on fructose, the cells formed large intracellular granules which after extraction yielded glucose by either acid or enzymatic hydrolysis. The endogenous polymer was subsequently metabolized, and after overnight incubation of the cells in buffer, the glucan granules were no longer detectable by electron microscopy. Anaerobically, washed cells grown previously on fructose fermented this sugar to a mixture of lactic, acetic, and butyric acids, and little intracellular glucan was formed. Aerobically, the cells slowly metabolized fructose to acetate. Provision of glutamic acid as an additional energy (ATP) source elicited rapid synthesis of polymer by glycolyzing cells. Intracellular granules were not present in glutamate-grown cells, and under anaerobic conditions, the resting cells failed to metabolize [14C] fructose. However, the addition of glutamic acid to the suspension resulted in the rapid accumulation of sugar by the cells. Approximately 15% of the 14C-labeled material was extractable with boiling water, and by 31P nuclear magnetic resonance spectroscopy, this phosphorylated derivative was identified as [14C]fructose-1-phosphate. The nonextractable material represented [14C]glucan polymer. Fructose-1-phosphate kinase activity in fructose-grown cells was fivefold greater than that in glutamate-grown cells. We suggest that the activity of fructose-1-phosphate kinase and the availability of ATP regulate the flow of fructose into either the glycolytic or polymer-synthesizing pathway in F. nucleatum.

Cytoplasmic Granules↗

PubMed1991

Peptidoglycan precursor from Fusobacterium nucleatum contains lanthionine.

Fusobacterium nucleatum was grown in the presence of [14C]UDP. By means of sequential precipitation and chromatographic separation of the cytoplasmic content, a peptidoglycan [14C]UDP pentapeptide containing lanthionine was isolated. This finding indicates that lanthionine is synthesized and incorporated as such during the assembly of the peptidoglycan.

Alanine↗

PubMed1992

Sucrose fermentation by Fusobacterium mortiferum ATCC 25557: transport, catabolism, and products.

Studies of sucrose utilization by Fusobacterium mortiferum ATCC 25557 have provided the first definitive evidence for phosphoenolpyruvate-dependent sugar:phosphotransferase activity in the family Bacteroidaceae. The phosphoenolpyruvate-dependent sucrose:phosphotransferase system and the two enzymes required for the dissimilation of sucrose 6-phosphate are induced specifically by growth of F. mortiferum on the disaccharide. Monomeric sucrose 6-phosphate hydrolase (M(r), 52,000) and a dimeric ATP-dependent fructokinase (subunit M(r), 32,000) have been purified to electrophoretic homogeneity. The physicochemical and catalytic properties of these enzymes have been examined, and the N-terminal amino acid sequences for both proteins are reported. The characteristics of sucrose 6-phosphate hydrolase and fructokinase from F. mortiferum are compared with the same enzymes from both gram-positive and gram-negative species. Butyric, acetic, and D-lactic acids are the end products of sucrose fermentation by F. mortiferum. A pathway is proposed for the translocation, phosphorylation, and metabolism of sucrose by this anaerobic pathogen.

Acetates↗

PubMed1993

Localization of the Fusobacterium nucleatum T18 adhesin activity mediating coaggregation with Porphyromonas gingivalis T22.

Adherence of pathogenic bacteria is often an essential first step in the infectious process. The ability of bacteria to adhere to one another, or to coaggregate, may be an important factor in their ability to colonize and function as pathogens in the periodontal pocket. Previously, a strong and specific coaggregation was demonstrated between two putative periodontal pathogens, Fusobacterium nucleatum and Porphyromonas gingivalis. The interaction appeared to be mediated by a protein adhesin on the F. nucleatum cells and a carbohydrate receptor on the P. gingivalis cells. In this investigation, we have localized the adhesin activity of F. nucleatum T18 to the outer membrane on the basis of the ability of F. nucleatum T18 vesicles to coaggregate with whole cells of P. gingivalis T22 and the ability of the outer membrane fraction of F. nucleatum T18 to inhibit coaggregation between whole cells of F. nucleatum T18 and P. gingivalis T22. Proteolytic pretreatment of the F. nucleatum T18 outer membrane fraction resulted in a loss of coaggregation inhibition, confirming the proteinaceous nature of the adhesin. The F. nucleatum T18 outer membrane fraction was found to be enriched for several proteins, including a 42-kDa major outer membrane protein which appeared to be exposed on the bacterial cell surface. Fab fragments prepared from antiserum raised to the 42-kDa outer membrane protein were found to partially but specifically block coaggregation. These data support the conclusion that the 42-kDa major outer membrane protein of F. nucleatum T18 plays a role in mediating coaggregation with P. gingivalis T22.

Antibodies, Bacterial↗

PubMed1994

Phosphoenolpyruvate-dependent maltose:phosphotransferase activity in Fusobacterium mortiferum ATCC 25557: specificity, inducibility, and product analysis.

Phosphoenolypyruvate-dependent maltose:phosphotransferase activity was induced in cells of Fusobacterium mortiferum ATCC 25557 during growth on maltose. The disaccharide was rapidly metabolized by washed cells maintained under anaerobic conditions, but fermentation ceased immediately upon exposure of the cell suspension to air. Coincidentally, high levels of a phosphorylated derivative accumulated within the cells. Chemical and enzymatic analyses, in conjunction with data from 1H, 13C, and 31P nuclear magnetic resonance spectroscopy, established the structure of the purified compound as 6-O-phosphoryl-alpha-D-glucopyranosyl-(1-4)-D-glucose (maltose 6-phosphate). A method for the preparation of substrate amounts of this commercially unavailable disaccharide phosphate is described. Permeabilized cells of F. mortiferum catalyzed the phosphoenolpyruvate-dependent phosphorylation of maltose under aerobic conditions. However, the hydrolysis of maltose 6-phosphate (to glucose 6-phosphate and glucose) by permeabilized cells or cell-free preparations required either an anaerobic environment or addition of dithiothreitol to aerobic reaction mixtures. The first step in dissimilation of the phosphorylated disaccharide appears to be catalyzed by an oxygen-sensitive maltose 6-phosphate hydrolase. Cells of F. mortiferum, grown previously on maltose, fermented a variety of alpha-linked glucosides, including maltose, turanose, palatinose, maltitol, alpha-methylglucoside, trehalose, and isomaltose. Conversely, cells grown on the separate alpha-glucosides also metabolized maltose. For this anaerobic pathogen, we suggest that the maltose:phosphotransferase and maltose 6-phosphate hydrolase catalyze the phosphorylative translocation and cleavage not only of maltose but also of structurally analogous alpha-linked glucosides.

Aerobiosis↗

PubMed1995

Purification from Fusobacterium mortiferum ATCC 25557 of a 6-phosphoryl-O-alpha-D-glucopyranosyl:6-phosphoglucohydrolase that hydrolyzes maltose 6-phosphate and related phospho-alpha-D-glucosides.

6-Phosphoryl-O-alpha-D-glucopyranosyl:6-phosphoglucohydrolase (6-phospho-alpha-glucosidase) has been purified from Fusobacterium mortiferum ATCC 25557. p-Nitrophenyl-alpha-D-glucopyranoside 6-phosphate (pNP alpha Glc6P) served as the chromogenic substrate for detection and assay of enzyme activity. The O2-sensitive, metal-dependent phospho-alpha-glucosidase was stabilized during purification by inclusion of dithiothreitol and Mn2+ ion in chromatography buffers. Various 6-phosphoryl-O-alpha-linked glucosides, including maltose 6-phosphate, pNP alpha Glc6P, trehalose 6-phosphate, and sucrose 6-phosphate, were hydrolyzed by the enzyme to yield D-glucose 6-phosphate and aglycone moieties in a 1:1 molar ratio. 6-Phospho-alpha-glucosidase (M(r) of approximately 49,000; pI of approximately 4.9) is activated by Fe2+, Mn2+, Co2+, and Ni2+, and the maximum rate of pNP alpha Glc6P hydrolysis occurs at 40 degrees C within the pH range 7.0 to 7.5. The sequence of the first 32 amino acids of 6-phospho-alpha-glucosidase exhibits 67% identity (90% similarity) to that deduced for the N terminus of a putative phospho-beta-glucosidase (designated ORF f212) encoded by glvG in Escherichia coli. Western blots involving highly specific polyclonal antibody against 6-phospho-alpha-glucosidase and spectrophotometric analyses with pNP alpha Glc6P revealed only low levels of the enzyme in glucose-, mannose-, or fructose-grown cells of F. mortiferum. Synthesis of 6-phospho-alpha-glucosidase increased dramatically during growth of the organism on alpha-glucosides, such as maltose, alpha-methylglucoside, trehalose, turanose, and palatinose.

Amino Acid Sequence↗

PubMed1997

6-phospho-alpha-D-glucosidase from Fusobacterium mortiferum: cloning, expression, and assignment to family 4 of the glycosylhydrolases.

The Fusobacterium mortiferum malH gene, encoding 6-phospho-alpha-glucosidase (maltose 6-phosphate hydrolase; EC 3.2.1.122), has been isolated, characterized, and expressed in Escherichia coli. The relative molecular weight of the polypeptide encoded by malH (441 residues; Mr of 49,718) was in agreement with the estimated value (approximately 49,000) obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the enzyme purified from F. mortiferum. The N-terminal sequence of the MalH protein obtained by Edman degradation corresponded to the first 32 amino acids deduced from the malH sequence. The enzyme produced by the strain carrying the cloned malH gene cleaved [U-14C]maltose 6-phosphate to glucose 6-phosphate (Glc6P) and glucose. The substrate analogs p-nitrophenyl-alpha-D-glucopyranoside 6-phosphate (pNP alphaGlc6P) and 4-methylumbelliferyl-alpha-D-glucopyranoside 6-phosphate (4MU alphaGlc6P) were hydrolyzed to yield Glc6P and the yellow p-nitrophenolate and fluorescent 4-methylumbelliferyl aglycons, respectively. The 6-phospho-alpha-glucosidase expressed in E. coli (like the enzyme purified from F. mortiferum) required Fe2+, Mn2+, Co2+, or Ni2+ for activity and was inhibited in air. Synthesis of maltose 6-phosphate hydrolase from the cloned malH gene in E. coli was modulated by addition of various sugars to the growth medium. Computer-based analyses of MalH and its homologs revealed that the phospho-alpha-glucosidase from F. mortiferum belongs to the seven-member family 4 of the glycosylhydrolase superfamily. The cloned 2.2-kb Sau3AI DNA fragment from F. mortiferum contained a second partial open reading frame of 83 residues (designated malB) that was located immediately upstream of malH. The high degree of sequence identity of MalB with IIB(Glc)-like proteins of the phosphoenol pyruvate dependent:sugar phosphotransferase system suggests participation of MalB in translocation of maltose and related alpha-glucosides in F. mortiferum.

Amino Acid Sequence↗

PubMed1997

Phospho-beta-glucosidase from Fusobacterium mortiferum: purification, cloning, and inactivation by 6-phosphoglucono-delta-lactone.

6-Phosphoryl-beta-D-glucopyranosyl:6-phosphoglucohydrolase (P-beta-glucosidase, EC 3.2.1.86) has been purified from Fusobacterium mortiferum. Assays for enzyme activity and results from Western immunoblots showed that P-beta-glucosidase (Mr, 53,000; pI, 4.5) was induced by growth of F. mortiferum on beta-glucosides. The novel chromogenic and fluorogenic substrates, p-nitrophenyl-beta-D-glucopyranoside-6-phosphate (pNPbetaGlc6P) and 4-methylumbelliferyl-beta-D-glucopyranoside-6-phosphate (4MUbetaGlc6P), respectively, were used for the assay of P-beta-glucosidase activity. The enzyme hydrolyzed several P-beta-glucosides, including the isomeric disaccharide phosphates cellobiose-6-phosphate, gentiobiose-6-phosphate, sophorose-6-phosphate, and laminaribiose-6-phosphate, to yield glucose-6-phosphate and appropriate aglycons. The kinetic parameters for each substrate are reported. P-beta-glucosidase from F. mortiferum was inactivated by 6-phosphoglucono-delta-lactone (P-glucono-delta-lactone) derived via oxidation of glucose 6-phosphate. The pbgA gene that encodes P-beta-glucosidase from F. mortiferum has been cloned and sequenced. The first 42 residues deduced from the nucleotide sequence matched those determined for the N terminus by automated Edman degradation of the purified enzyme. From the predicted sequence of 466 amino acids, two catalytically important glutamyl residues have been identified. Comparative alignment of the amino acid sequences of P-beta-glucosidase from Escherichia coli and F. mortiferum indicates potential binding sites for the inhibitory P-glucono-delta-lactone to the enzyme from F. mortiferum.

Amino Acid Sequence↗

PubMed2000

Native plasmids of Fusobacterium nucleatum: characterization and use in development of genetic systems.

Three native plasmids of Fusobacterium nucleatum were characterized, including DNA sequence analysis of one plasmid, pFN1. A shuttle plasmid, pHS17, capable of transforming Escherichia coli and F. nucleatum ATCC 10953 was constructed with pFN1. pHS17 was stably maintained in the F. nucleatum transformants, and differences in the transformation efficiencies suggested the presence of a restriction-modification system in F. nucleatum.

Amino Acid Sequence↗

PubMed2002

Genome sequence and analysis of the oral bacterium Fusobacterium nucleatum strain ATCC 25586.

We present a complete DNA sequence and metabolic analysis of the dominant oral bacterium Fusobacterium nucleatum. Although not considered a major dental pathogen on its own, this anaerobe facilitates the aggregation and establishment of several other species including the dental pathogens Porphyromonas gingivalis and Bacteroides forsythus. The F. nucleatum strain ATCC 25586 genome was assembled from shotgun sequences and analyzed using the ERGO bioinformatics suite (http://www.integratedgenomics.com). The genome contains 2.17 Mb encoding 2,067 open reading frames, organized on a single circular chromosome with 27% GC content. Despite its taxonomic position among the gram-negative bacteria, several features of its core metabolism are similar to that of gram-positive Clostridium spp., Enterococcus spp., and Lactococcus spp. The genome analysis has revealed several key aspects of the pathways of organic acid, amino acid, carbohydrate, and lipid metabolism. Nine very-high-molecular-weight outer membrane proteins are predicted from the sequence, none of which has been reported in the literature. More than 137 transporters for the uptake of a variety of substrates such as peptides, sugars, metal ions, and cofactors have been identified. Biosynthetic pathways exist for only three amino acids: glutamate, aspartate, and asparagine. The remaining amino acids are imported as such or as di- or oligopeptides that are subsequently degraded in the cytoplasm. A principal source of energy appears to be the fermentation of glutamate to butyrate. Additionally, desulfuration of cysteine and methionine yields ammonia, H(2)S, methyl mercaptan, and butyrate, which are capable of arresting fibroblast growth, thus preventing wound healing and aiding penetration of the gingival epithelium. The metabolic capabilities of F. nucleatum revealed by its genome are therefore consistent with its specialized niche in the mouth.

Amino Acids↗

PubMed1979

Medium for selective isolation of Fusobacterium nucleatum from human periodontal pockets.

A selective medium, CVE agar, was developed for the isolation of Fusobacterium nucleatum from subgingival plaque of periodontally diseased patients. The medium contained 1.0% Trypticase (BBL Microbiology Systems), 0.5% yeast extract, 0.5% NaCl, 0.2% glucose, 0.02% L-tryptophan, 1.5% agar, and 5% defibrinated whole sheep blood. Erythromycin and crystal violet were added as the selective inhibitory agents at concentrations of 4 and 5 micrograms/ml, respectively. The medium permitted almost total recovery of F. nucleatum when compared with a nonselective medium and suppressed the recovery of most remaining species by nonselective medium and suppressed the recovery of most remaining species by 6 to 8 orders of magnitude. Microorganisms suppressed to a lesser degree included Selenomonas sputigena, Actinobacillus actinomycetemcomitans, Eikenella corrodens, and some strains of Peptostreptococcus. The distinct colonial morphology of F. nucleatum on CVE agar made differentiation relatively easy when contaminants were present. With this medium, F. nucleatum was enumerated from 278 subgingival plaque samples and accounted for less than 1.0 to greater than 25% of the cultivatable microbiota.

Adolescent↗

PubMed1983

Fusobacterium nucleatum pericarditis.

A pericardial effusion was diagnosed by echocardiography in a 49 year old man who suffered acute cough, orthopnea, and chest pain. Because of a positive tuberculin skin test, mycobacteria were initially suspected as the cause of the pericarditis. The patient was therefore treated with antituberculosis drugs. The pericardial effusion failed to resolve, however, and pericardiectomy was performed. Culture of the pericardial fluid yielded pure Fusobacterium nucleatum growth. The patient responded to antibiotic therapy and was in good health 3 weeks after being discharged from the hospital. This represents the first report of F. nucleatum pericarditis.

Fusobacterium Infections↗

PubMed1986

Enhancement of Bacteroides intermedius growth by Fusobacterium necrophorum.

Previous work from this laboratory has demonstrated the persistence of Bacteroides intermedius in the livers of mice receiving an intraperitoneal inoculum of B. intermedius and Fusobacterium necrophorum. This study was undertaken to determine whether F. necrophorum enhanced the in vitro growth of B. intermedius. Tryptose phosphate broth did not support the growth of B. intermedius alone, but the bacterium did survive in a tryptose phosphate broth culture of F. necrophorum. B. intermedius cultured in F. necrophorum-conditioned tryptose phosphate broth grew impressively, reaching maximal absorbance at 24 h after inoculation. The growth of B. intermedius in F. necrophorum-conditioned tryptose phosphate broth was proportional to the amount of conditioned medium present. The B. intermedius growth-stimulating factor was detectable in conditioned medium 8 h after inoculation with F. necrophorum and could be detected throughout the 96-h incubation period. Growth-factor-active fractions eluted from a Sephadex G-100 column did not absorb at 280 nm and were retained on the column until 4 column volumes were eluted. The growth factor was nondialyzable and stable to boiling, lyophilization, extraction with hot aqueous phenol, and trypsin digestion. The factor was inactivated by exposure to pH 2.0 in the pepsin digestion protocol. Significant amounts of hexose, methyl pentose, and 2-keto-3-deoxyoctonate were detected in pooled growth-factor-active fractions eluted from the Sephadex column. This pool was also active in the Limulus lysate endotoxin assay. These results suggest that the B. intermedius growth-stimulating factor produced by F. necrophorum is a lipopolysaccharide.

Bacteroides↗

PubMed1999

Coaggregation of Candida dubliniensis with Fusobacterium nucleatum.

The binding of microorganisms to each other and oral surfaces contributes to the progression of microbial infections in the oral cavity. Candida dubliniensis, a newly characterized species, has been identified in human immunodeficiency virus-seropositive patients and other immunocompromised individuals. C. dubliniensis phenotypically resembles Candida albicans in many respects yet can be identified and differentiated as a unique Candida species by phenotypic and genetic profiles. The purpose of this study was to determine oral coaggregation (CoAg) partners of C. dubliniensis and to compare these findings with CoAg of C. albicans under the same environmental conditions. Fifteen isolates of C. dubliniensis and 40 isolates of C. albicans were tested for their ability to coaggregate with strains of Fusobacterium nucleatum, Peptostreptococcus micros, Peptostreptococcus magnus, Peptostreptococcus anaerobius, Porphyromonas gingivalis, and Prevotella intermedia. When C. dubliniensis and C. albicans strains were grown at 37 degrees C on Sabouraud dextrose agar, only C. dubliniensis strains coaggregated with F. nucleatum ATCC 49256 and no C. albicans strains showed CoAg. However, when the C. dubliniensis and C. albicans strains were grown at 25 or 45 degrees C, both C. dubliniensis and C. albicans strains demonstrated CoAg with F. nucleatum. Heating the C. albicans strains (grown at 37 degrees C) at 85 degrees C for 30 min or treating them with dithiothreitol allowed the C. albicans strains grown at 37 degrees C to coaggregate with F. nucleatum. CoAg at all growth temperatures was inhibited by mannose and alpha-methyl mannoside but not by EDTA or arginine. The CoAg reaction between F. nucleatum and the Candida species involved a heat-labile component on F. nucleatum and a mannan-containing heat-stable receptor on the Candida species. The CoAg reactions between F. nucleatum and the Candida species may be important in the colonization of the yeast in the oral cavity, and the CoAg of C. dubliniensis by F. nucleatum when grown at 37 degrees C provides a rapid, specific, and inexpensive means to differentiate C. dubliniensis from C. albicans isolates in the clinical laboratory.

Amino Acids↗