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A S Naidu

Publications and source records attributed to A S Naidu.

At least 19 recordsLinked to original sources
PubMed2005

Antimicrobial action of carvacrol at different stages of dual-species biofilm development by Staphylococcus aureus and Salmonella enterica serovar Typhimurium.

The effects of carvacrol, a natural biocide, on dual-species biofilms formed by Staphylococcus aureus and Salmonella enterica serovar Typhimurium were investigated with a constant-depth film fermentor. Biofilm development reached a quasi-steady state in 12 days at 25 degrees C with S. aureus predominance ( approximately 99%). Cryosectional analysis detected viable S. aureus and S. enterica serovar Typhimurium at depths of 320 and 180 mum from the film surface, respectively. Carvacrol pulses (1.0 mmol/h) inhibited S. aureus by 2.5 log CFU/biofilm during the early stages of film formation, ultimately causing a significant reduction (P < 0.001) of the staphylococcal population at quasi-steady state. Initial carvacrol pulsing elicited a 3 log CFU/biofilm reduction in viable S. enterica serovar Typhimurium, and additional periodic carvacrol pulses instigated significant inhibition of salmonellae (1 to 2 log CFU/biofilm) during biofilm development. Carvacrol pulsing reduced protein levels fivefold (P < 0.001) during initial biofilm development. Comparative studies with a peroxide-based commercial sanitizer (Spor-Klenz RTU) revealed that this commercial sanitizer was more biocidal than carvacrol during early biofilm development. When the biofilm reached quasi-steady state, however, periodic pulses with 1 mmol of carvacrol per h (P = 0.021) elicited a significantly higher inhibition than Spor-Klenz RTU (P = 0.772). Dual-species microcolonies formed under the influence of continuously fed low carvacrol concentrations (1.0 mmol/h) but failed to develop into a mature quasi-steady-state biofilm and did not reach any stage of film formation in the presence of high concentrations (5.0 mmol/h). These data show that carvacrol is an effective natural intervention to control dual-species biofilm formation.

Biofilms↗
PubMed2002

Reduction of sulfide, ammonia compounds, and adhesion properties of Lactobacillus casei strain KE99 in vitro.

The ability of Lactobacillus casei strain KE99 to reduce sulfide, ammonia, and to adhere to bio-surfaces was characterized and compared with three lactobacillus reference strains. Sulfide reduction by strain KE99 in MRS broth increased exponentially after 10-h growth and reached a maximum (>300 ppm reduction) within 48 h. KE99 demonstrated a maximum reduction of sulfide under anaerobic (341 ppm) growth conditions at pH 6.0-8.0 range. Maximum anaerobic reduction of sulfide was demonstrated by L. casei 393 at pH 7.0 (272 ppm); L. rhamnosus at pH 8.0 (277 ppm); and L. reuteri at pH 7.0 (244 ppm). KE99 reduced sulfide more (p < 0.0001) in MRS broth spiked with Na2S (374 ppm) than (NH4)2S (340 ppm) salts. Ammonia reduction by strain KE99 and the three lactobacillus reference strains in MRS broth was low. Ammonia reduction reached a maximum within 36 h and remained unchanged over extended incubations of 48 h to 72 h or further. KE99 reduced ammonium sulfate (37 ppm) more readily than the nitrate (31 ppm), hypophosphate (29 ppm), or chloride (20 ppm) salts of ammonia. KE99 and the three reference strains of lactobacilli demonstrated avid binding to Bio-coat (Cn type-I, Cn type-IV, laminin, fibronectin), Matrigel, and Caco-2 cell monolayers in vitro. The number of lactobacilli binding to Caco-2 was estimated at 74/cell with strain KE99, which was significantly higher compared with 40/cell (p < 0.0001), 26/cell (0.0001), and 64/cell (p < 0.002) with L. casei 393, L. reuteri, and L. rhamnosus, respectively. The interaction of KE99 to immobilized Cn type-I was saturable and reached an equilibrium within 1 h at room temperature. KE99 binding to Cn type-I occurred at a wide pH range and was biphasic with maximum binding at pH 5.5 and 7.5. Inhibition and binding-displacement experiments with different salts and sugars suggested that the KE99 binding to immobilized Cn type-I may involve a combination of electrostatic and lectin-type interactions. KE99 effectively detached the Cn-adherent E. coli O157:H7 in the range of 55% (ATCC43895) to 76% (ATCC43894). The binding-displacement values for L. casei 393, L. reuteri and L. rhamnosus to detach Cn-adherent E. coli O157:H7 (ATCC43894) were 66 +/- 4%, 59 +/- 2%, and 64 +/- 2%, respectively. Also, a reconstituted solution of the freeze-dried KE99 preparation effectively detached the Cn-adherent E. coli O157:H7 in a dose-dependent manner that reached a binding-displacement equilibrium of 85% at a 1% wt/vol KE99 concentration.

Ammonia↗
PubMed1999

Probiotic spectra of lactic acid bacteria (LAB).

Lactic acid bacteria (LAB) and their probio-active cellular substances exert many beneficial effects in the gastrointestinal tract. LAB prevent adherence, establishment, and replication of several enteric mucosal pathogens through several antimicrobial mechanisms. LAB also release various enzymes into the intestinal lumen and exert potential synergistic effects on digestion and alleviate symptoms of intestinal malabsoption. Consumption of LAB fermented dairy products with LAB may elicit antitumor effects. These effects are attributed to the inhibition of mutagenic activity; decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents; suppression of tumors; and the epidemiology correlating dietary regimes and cancer. Specific cellular components in LAB strains seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of reticuloendothelial system, augmentation of cytokine pathways and regulation of interleukins, and tumor necrosis factors. Oral administration of LAB is well tolerated and proven to be safe in 143 human clinical trials and no adverse effects were reported in any of the total 7,526 subjects studied during 1961-1998. In an effort to decrease the reliance on synthetic antimicrobials and control the emerging immunocompromised host population, the time has come to carefully explore the prophylactic and therapeutic applications of probiotic LAB.

Animals↗
PubMed1995

Lactoferrin interaction with Actinobacillus actinomycetemcomitans.

The interaction of lactoferrin with Actinobacillus actinomycetemcomitans was examined in a 125I-labeled protein binding assay. The binding of human and bovine lactoferrins reached maximum within 1 h. Lactoferrin binding to the bacterium was pH-dependent and reversible. Scatchard analysis indicated the existence of two different types of binding sites on the bacterium, one with a high affinity constant k alpha approximately 8.8 x 10(-7) M) and the other with a low one (k alpha approximately 1.8 x 10(-6) M). Bacteria in the exponential phase of growth showed higher binding than cells in the stationary phase. Bacteria grown in medium containing serum and/or lysed erythrocytes bound lactoferrin to a lesser extent. Heat-inactivated serum, lysed erythrocytes and other proteins such as mucin and laminin inhibited lactoferrin binding to A. actinomycetemcomitans in a competitive binding assay. Sodium dodecyl sulfate polyacrylamide-gel electrophoresis and Western blot analysis of the cell envelope as well as the outer membrane of A. actinomycetemcomitans revealed lactoferrin-reactive protein bands at 29 kDa and 16.5 kDa. The 29-kDa band displayed a heat-modifiable lactoferrin-reactive form with a molecular weight of 34 kDa. Neither proteinase K-treated cell envelope nor lipopolysaccharide of this bacterium showed reactivity with lactoferrin. These data suggests a specific interaction of lactoferrin with outer membrane proteins of A. actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans↗
PubMed1994

Lactoferrin interaction with salmonellae potentiates antibiotic susceptibility in vitro.

Interaction of lactoferrin (Lf) with the cell envelope (CE) and outer membrane (OM) of Salmonella typhimurium-type strain ATCC13311 was tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western-blot analyses. The peroxidase-labeled bovine Lf (BLf) and human Lf both recognized a heat-modifiable protein with an estimated molecular mass of 38 kD in the OM. Simultaneous immunoblotting with an antiporin monoclonal antibody specific for a conserved porin domain in members of enterobacteriaceae confirmed that the Lf-binding protein is a porin. Such Lf-binding porin proteins (37-39 kD range) were readily detected in nine other common Salmonella species: S. dublin, S. panama, S. rostock, S. abony, S. hartford, S, kentucky, S. pullorum, S. thompson, and S. virchow. The latter six species also demonstrated one to three weak Lf-reactive bands of low molecular weight in their CE. The antibiotic susceptibility of Salmonella in the presence of Lf was examined. A mixture containing sub-minimum inhibitory concentration (MIC) levels of Lf (MIC/4) and cefuroxime (MIC/2) inhibited the bacterial growth. Lf strongly potentiated the action of erythromycin (eightfold), whereas it increased the activity only by two-fold for ampicillin, ciprofloxacin, chloramphenicol, and rifampicin; similarly, these antibiotics also reduced the MIC of BLf by twofold in S. typhimurium. Such antimicrobial potentiation was not observed with BLf mixtures containing cefalexin, gentamycin, or polymyxin B against strain ATCC13311. BLf and cefuroxime also demonstrated potentiation of varying degrees (two to 16-fold) with nine other Salmonella species. These data established the binding of Lf to porins in salmonellae and a potentiation effect of Lf with certain antibiotics.

Anti-Bacterial Agents↗
PubMed1994

Effect of lactoferrin on interaction of Prevotella intermedia with plasma and subepithelial matrix proteins.

A lactoferrin-binding protein with an estimated molecular mass of 57 kDa was identified in the cell envelope of Prevotella intermedia by gel electrophoresis and Western-blot analysis. Peroxidase-labeled bovine lactoferrin and human lactoferrin showed similar specific binding to this protein. Whole cells of P. intermedia were also examined for interactions with 5 125I-labeled plasma and subepithelial matrix proteins. A high degree of binding was found with fibronectin, collagen type I and type IV and laminin, whereas a moderate interaction was detected with fibrinogen. The ability of bovine lactoferrin to affect the interactions of the above proteins with P. intermedia was examined. In the presence of unlabeled bovine lactoferrin, a dose-dependent inhibition of binding was observed with all 5 proteins tested. Unlabeled bovine lactoferrin also dissociated the bacterial complexes with these proteins. The complexes with laminin or collagen type I were more effectively dissociated than fibronectin or fibrinogen, whereas the interaction with collagen type IV was affected to a lesser extent. A strain-dependent variation in the effect of bovine lactoferrin was observed. These data establish the presence of a specific lactoferrin-binding protein in the cell envelope of P. intermedia. The ability of lactoferrin to inhibit the binding of some plasma and subepithelial matrix proteins to P. intermedia could be a protective mechanism against the establishment of this pathogen in the periodontal pocket.

Animals↗
PubMed1994

Lactoferrin binds to porins OmpF and OmpC in Escherichia coli.

Lactoferrin (Lf) is an iron-binding antimicrobial protein present in milk and on mucosal surfaces, with a suggested role in preimmune host defense. Certain strains of Escherichia coli (bacterial whole cells) demonstrate specific interaction with 125I-labeled Lf. A band with a mass of approximately 37 kDa, which was reactive with horseradish peroxidase-labeled Lf, was identified in the boiled cell envelope and outer membrane preparations of an Lf-binding E. coli strain, E34663, and a non-Lf-binding strain, HH45, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting (immunoblotting). Such a band was not detected in the unboiled native cell envelope and outer membrane preparations. The molecular mass and the property of heat modifiability suggested that the Lf-binding proteins were porins. The native trimeric form of porin OmpF isolated from strain B6 and its dissociated monomeric form both reacted with horseradish peroxidase-labeled Lf and with monoclonal antibodies specific for OmpF. Furthermore, by using E. coli constructs with defined porin phenotypes, OmpF and OmpC were identified as the Lf-binding proteins by urea-SDS-PAGE and Western blotting and by 125I-Lf binding studies with intact bacteria. These data establish that Lf binds to porins, a class of well-conserved molecules common in E. coli and many other gram-negative bacteria. However, in certain strains of E. coli these pore-forming proteins are shielded from Lf interaction.

Escherichia coli↗
PubMed1993

Relationship between antibacterial activity and porin binding of lactoferrin in Escherichia coli and Salmonella typhimurium.

The effect of lactoferrin (Lf) on bacterial growth was tested by measuring conductance changes in the cultivation media by using a Malthus-AT system and was compared with the magnitude of 125I-labeled Lf binding in 15 clinical isolates of Escherichia coli. The binding property was inversely related to the change in bacterial metabolic rate (r = 0.91) and was directly related to the degree of bacteriostasis (r = 0.79). The magnitude of Lf-bacterium interaction showed no correlation with the MIC of Lf. In certain strains, Lf at supraoptimal levels reduced the bacteriostatic effect. Thus, the Lf concentration in the growth media was critical for the antibacterial effect. The cell envelopes of Salmonella typhimurium 395MS with smooth lipopolysaccharide (LPS) and its five isogenic rough mutants revealed 38-kDa porin proteins as peroxidase-labeled-Lf-reactive components in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (ligand blot) analysis. However, in the whole cell binding assay, parent strain 395MS demonstrated a very low interaction with 125I-Lf. On the other hand, Lf interaction gradually increased in correspondence with the decrease in LPS polysaccharide moiety in the isogenic rough mutants. Conductance measurement studies revealed that the low-level-Lf-binding (low-Lf-binding) strain 395MS with smooth LPS was relatively insusceptible to Lf, while the high-Lf-binding mutant Rd was more susceptible to Lf. These data suggested a correlation between Lf binding to porins and the Lf-mediated antimicrobial effect. The polysaccharide moiety of LPS shielded porins from the Lf interaction and concomitantly decreased the antibacterial effect.

Animals↗
PubMed1993

Thermal behavior of bovine lactoferrin in water and its relation to bacterial interaction and antibacterial activity.

Heat-induced enthalpy changes in different forms of bovine lactoferrin in water were examined by differential scanning calorimetry. Two thermal transitions with varying enthalpies were observed, depending on the iron-binding status of the protein. Iron-saturated lactoferrin was more resistant to heat-induced changes than was the apolactoferrin. Native lactoferrin had two transitional peaks, and pasteurization affected only the low temperature transition. Iron-saturated lactoferrin revealed a single transitional peak that was resistant to pasteurization. However, both protein forms were completely denatured by UHT. The effect of pasteurization and UHT on the protein interaction capacity with bacteria was examined in a 125I-labeled lactoferrin binding-inhibition assay. The ability of native and iron-saturated lactoferrins to bind various bacterial species was unaffected by pasteurization. However, UHT treatment decreased this interaction capacity. Native lactoferrins, both unheated and pasteurized, showed similar antibacterial properties and moderately inhibited Escherichia coli. However, this inhibitory capacity was lost after UHT treatment. Finally, iron-saturated lactoferrin did not inhibit bacterial growth; neither pasteurization nor UHT could change this property. Thus, UHT seems to affect structural as well as certain biological properties of both native and iron-saturated bovine lactoferrins, and pasteurization seems to be a treatment of choice for products containing this protein.

Animals↗
PubMed1992

Identification of a human lactoferrin-binding protein in Staphylococcus aureus.

Human lactoferrin (HLf) is an iron-binding protein with antimicrobial activity that is present in high concentrations in milk and various exocrine secretions. HLf is also an acute-phase protein secreted by polymorphonuclear leucocytes, and its binding to a large number of clinical isolates of Staphylococcus aureus has been described recently from our laboratory. We have now characterised the HLf-staphylococcal interaction in S. aureus strain MAS-89. The binding of 125I-HLf to strain MAS-89 reached saturation in less than 90 min and was maximal between pH 4 and 9. Unlabelled HLf displaced 125I-HLf binding. Various plasma and subepithelial matrix proteins, such as IgG, fibrinogen, fibronectin, collagen and laminin, which are known to interact specifically with S. aureus, did not interfere with HLf binding. A Scatchard plot was non-linear; this implied a low affinity (1.55 x 10(7) L/mol) and a high affinity (2.70 x 10(8) L/mol) binding mechanism. We estimated that there were c. 5700 HLf binding sites/cell. The staphylococcal HLf-binding protein (HLf-BP) was partially susceptible to proteolytic enzymes or periodate treatment and was resistant to glycosidases. An active HLf-BP with an apparent Mr of c. 450 Kda was isolated from strain MAS-89 cell lysate by ion-exchange chromatography on Q-sepharose. In SDS-PAGE, the reduced HLf-BP was resolved into two components of 67 and 62 Kda. The two components demonstrated a positive reaction with HLf-HRPO in a Western blot. These data establish that there is a specific receptor for HLf in S. aureus.

Bacterial Proteins↗
PubMed1992

Detection of bacterial interaction with lactoferrin by an enzyme-linked ligand binding assay (ELBA).

An enzyme-linked ligand binding assay (ELBA) was devised to measure the interaction between bacteria and human (H) or bovine (B) lactoferrin (Lf) linked to horseradish peroxidase. Reagents were calibrated for optimum colour development with o-phenylenediamine as chromophore and organisms that were either positive or negative in a radioisotope-labelled ligand binding assay (RLBA) with 125I-Lf. Good correlation of Lf binding (r = 0.89) was found between ELBA and RLBA with 169 randomly selected strains of Escherichia coli. A semi-quantitative scoring system for ELBA, corresponding to a similar system for RLBA, was established and shown to be valid for 517 strains from seven species of bacterial pathogens. ELBA was used to measure bacterial Lf binding-saturation and displacement kinetics and shown to be comparable with RLBA. ELBA may be a suitable method for examining the binding of Lf to bacteria without the need for radioactive isotopes.

Animals↗
PubMed1992

Laminin binding to Prevotella intermedia.

The interaction of laminin (Lm), a basement membrane protein abundant in the periodontium, with 66 strains of Prevotella intermedia isolated from diseased pockets, was tested in a 125I-labeled protein binding assay. The mean binding value was 28% of the total protein added. The binding significantly increased to 35% when the environmental pH decreased from 7 to 6. The Lm interaction was characterized in a highly binding (about 65%) strain, OMGS105. The binding was rapid and required about 1 min and 1-2 h for 50% and 100% equilibrium respectively. The 125I-Lm binding was maximum in the pH interval 3.0 to 6.5 and could not be displaced by unlabeled Lm or inhibited by other proteins and carbohydrates. The interaction was stable in the presence of NaCl or urea (concentrations up to 4 M) but was dissociated by > or = 1 M KSCN. The Lm-binding component was thermolabile and sensitive to proteolytic enzymes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western blot analysis revealed a approximately 62 kDa Lm-binding protein, both in the whole cell extract and the outer membrane preparation. Weaker binding was also observed to other proteins. These data establish the ability of P. intermedia to interact with Lm via certain cell surface proteins, a property that might contribute to the colonization of this bacterium in the periodontal pocket.

Bacterial Adhesion↗
PubMed1992

Lactoferrin-binding proteins in Shigella flexneri.

The ability of Shigella flexneri to interact with lactoferrin (Lf) was examined with a 125I-labeled protein-binding assay. The percent binding of human lactoferrin (HLf) and bovine lactoferrin (BLf) to 45 S. flexneri strains was 19 +/- 3 and 21 +/- 3 (mean +/- standard error of the mean), respectively. 125I-labeled HLf and BLf binding to strain M90T reached an equilibrium within 2 h. Unlabeled HLf and BLf displaced the 125I-HLf-bacteria interaction in a dose-dependent manner. The Lf-bacterium complex was uncoupled by KSCN or urea, but not by NaCl. The interaction was specific, and approximately 4,800 HLf binding sites (affinity constant [Ka], 690 nM) or approximately 5,700 BLf binding sites (Ka, 104 nM) per cell were estimated in strain M90T by a Scatchard plot analysis. The native cell envelope (CE) and outer membrane (OM) did not reveal Lf-binding components in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, after being boiled, the CE and OM preparations showed three distinct horseradish peroxidase-Lf reactive bands of about 39, 22, and 16 kDa. The 39-kDa component was also reactive to a monoclonal antibody specific for porin (PoI) proteins of members of the family Enterobacteriaceae. The Lf-binding protein pattern was similar with BLf or HLf, for Crb+ and Crb- strains. The protein-Lf complex was dissociable by KSCN or urea and was stable after treatment with NaCl. Variation (loss) in the O chain of lipopolysaccharide (LPS) markedly enhanced the Lf-binding capacity in the isogenic rough strain SFL1070-15 compared with its smooth parent strain, SFL1070. These data establish that Lf binds to specific components in the bacterial OM; the heat-modifiable, anti-PoI-reactive, and LPS-associated properties suggested that the Lf-binding proteins are porins in S. flexneri.

Bacterial Adhesion↗
PubMed1991

Specific binding of lactoferrin to Aeromonas hydrophila.

The interaction of lactoferrin (Lf) with Aeromonas hydrophila (n = 28) was tested in a 125I-labeled protein-binding assay. The mean per cent binding values for human Lf (HLf) and bovine Lf (BLf) were 13.4 +/- 2.0 (SEM), and 17.5 +/- 2.7 (SEM), respectively. The Lf binding was characterized in type strain A. hydrophila subsp. hydrophila CCUG 14551. The HLf and BLf binding reached a complete saturation within 2 h. Unlabeled HLf and BLf displaced 125I-HLf binding in a dose-dependent manner, and more effectively by the heterologous (1 microgram for 50% inhibition) than the homologous (10 micrograms for 50% inhibition) ligand. Apo- and holo-forms of HLf and BLf both inhibited more than 80%, while mucin caused approx. 50% inhibition of the HLf binding. Various other proteins (including transferrin) or carbohydrates did not block the binding. Two HLf-binding proteins with an estimated molecular masses of 40 kDa and 30 kDa were identified in a boiled-cell-envelope preparation, while the unboiled cell envelope demonstrated a short-ladder pattern at the top of the separating gel and a second band at approx. 60 kDa position. These data establish a specific interaction of Lf and the Lf-binding proteins seem to be porins in A. hydrophila.

Aeromonas hydrophila↗
PubMed1991

Human lactoferrin binding in clinical isolates of Staphylococcus aureus.

Human lactoferrin (HLf) is an iron-binding protein and a host-defence component at the mucosal surface. Recently, a specific receptor for HLf has been identified on a strain of Staphylococcus aureus associated with toxic shock syndrome. We have looked for the occurrence of 125I-HLf binding among 489 strains of S. aureus isolated from various clinical sources. HLf binding was common among S. aureus strains associated with furunculosis (94.3%), toxic shock syndrome (94.3%), endocarditis (83.3%) and septicaemia (82.8%) and other (nasal, vaginal or ocular) infections (96.1%) with a mean binding (in fmol) of 29.1, 21.9, 16.9, 22.2 and 29.2 respectively; the differences between mean HLf binding values of 29.1-29.2, 21.9-22.2 and 16.9 were significant. Furunculosis-associated (low-invasive or localised) isolates were high-to-moderate binders of HLf; 50% gave positive results at a threshold of greater than 31 fmol of 125I-HLf bound. In contrast, endocarditis-associated (high-invasive or systemic) isolates demonstrated low binding and did not bind 125I-HLf at the above threshold level. S. aureus recognised human or bovine Lf. However, bound 125I-HLf was more effectively inhibited in a dose-dependent manner by unlabelled bovine Lf than by homologous HLf. Binding of 125I-HLf to staphylococci was optimal with organisms grown in agar compared with those from broth cultures. The binding capacity of S. aureus was abolished when strains were grown on carbohydrate- and salt-rich agar media. HLf-binding ability of S. aureus did not correlate with fibronectin, fibrinogen, immunoglobulin G or laminin binding.

Culture Media↗
PubMed1991

Human lactoferrin binding to Porphyromonas gingivalis, Prevotella intermedia and Prevotella melaninogenica.

Human isolates of Porphyromonas gingivalis (n = 16), Prevotella intermedia n = 82) and Prevotella melaninogenica (n = 18) from diseased periodontal pockets were examined for interaction with human lactoferrin (HLf) in a standardized 125I-labeled protein binding assay. The highest HLf binding was found in P. intermedia strains, followed by P. gingivalis and P. melaninogenica. Further characterization of the interaction was performed with 1 representative strain from each species. HLf binding to P. gingivalis reached a saturation instantly and was optimal at pH 5.0-6.5. The corresponding values for P. melaninogenica were 90 min and pH 3.0-5.5. The HLf binding to the 2 strains seem to be nonspecific. In contrast, P. intermedia demonstrated specific binding, and a time-saturability within 60 min with an optimal uptake at pH 6.0-7.5. Scatchard analysis implied 45,000 receptors per cell with an affinity constant of 5.5 x 10(-7) M on P. intermedia strain 4H. The binding capacity in all 3 strains was affected by the culture medium. HLf binding components in these strains were susceptible to heat or proteases. Binding was eliminated in P. gingivalis and was enhanced in P. intermedia and P. melaninogenica by periodate treatment. Unlabeled HLf or bovine lactoferrin effectively displaced labeled HLf binding. Various proteins and carbohydrates did not inhibit HLf binding. Our data suggest that HLf binds to these periodontitis-associated species and that this mechanism is distinct from the previously known ligand interactions in oral bacteria.

Acute-Phase Proteins↗
PubMed1991

Correlation between human lactoferrin binding and colicin susceptibility in Escherichia coli.

Escherichia coli H10407 demonstrated low 125I-human lactoferrin (HLf) binding (7%) and was insusceptible to group A (A, E1, E2, E3, E6, and K) and group B (B, D, Ia, Ib, and V) colicins. Conversely, a spontaneous HLf high-binding (44%) variant, H10407(Lf), demonstrated an increase susceptibility to both colicin groups. Colicin-insusceptible E. coli wild-type strains 75ColT, 84ColT, and 981ColT showed a low degree of HLf binding, i.e., 4, 8, and 10%, respectively. The HLf binding capacity was high in the corresponding colicin-susceptible mutants 75ColS (43%), 84ColS (32%), and 981ColS (43%). Furthermore, HLf low- (less than 5%) and high- (greater than 35%) binding E. coli clinical isolates (10 in each category) were tested for susceptibility against 11 colicins. Colicin V susceptibility did not correlate with HLf binding in either categories. However, with the remaining colicins, three distinct HLf-binding, colicin susceptibility patterns were observed; (i) 10 of 10 HLf low-binding strains were colicin insusceptible, (ii) 6 of 10 HLf high-binding strains were also colicin insusceptible, and (iii) the remaining HLf high binders were highly colicin susceptible. Certain proteins in the cell envelope and outer membrane of wild-type H10407 (HLf low binder, colicin insusceptible) showed a lower mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis compared to the corresponding proteins of mutant H10407(Lf) (HLf high binder, colicin susceptible). These mobility differences were also associated with HLf-binding proteins in Western blot (ligand blot) analysis. The wild type showed a smooth form of lipopolysaccharide (LPS) with a distinct ladder of O-chains, compared to the rough LPS of the mutant.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗