Adhesion, autoaggregation and hydrophobicity of 13 strains of Bifidobacterium longum

To identify bacterial traits related to adhesion ability in human bifidobacteria, 13 strains of Bifidobacterium longum isolated from human gastric juice and intestine were studied. Strains were tested for their capability to adhere to Caco-2 cells and classified as adhesive (Adh+) or non-adhesive (Adh-). Adh+ and Adh- strains were then investigated for their autoaggregation ability and surface hydrophobicity. Comparing the properties of Adh+ and Adh-, we observed that strains were able to adhere to cell monolayers if they autoaggregate and manifest a good degree of hydrophobicity as determined by microbial adhesion to hydrocarbons. These two traits could be used for preliminary screening to identify potentially adherent isolates.     

In vitro effects of bovine lactoferrin on autoaggregation ability and surface hydrophobicity of bifidobacteria

Changes in autoaggregation ability and surface hydrophobicity of bifidobacteria with addition of bovine lactoferrin in liquid media were investigated. Lactoferrin addition caused loss of autoaggregation ability, disappearance of microscopic clusters and produced consistent turbidity in the cultured medium compared with control. Similar outcomes with addition of bovine lactoferrin hydrolysates (pepsin), bovine transferrin or ovotransferrin suggested that the effect is not lactoferrin-specific. On the other hand, addition of proteins, except bovine transferrin, did not alter surface hydrophobicity. These results indicate that one or more surface components involved in autoaggregation of bifidobacteria are proteins.     

The relationship between auto-agglutination, cell surface hydrophobicity and virulence of the fish pathogen Renibacterium salmoninarum

Abstract The cell surface hydrophobicity of Renibacterium salmoninarum strains was examined using a salt aggregation method. Those strains which were virulent in the test animal were sticky, auto-agglutinating and possessed a hydrophobic cell surface. Those strains with a low virulence were non-sticky, non-agglutinating and failed to aggregate in a high molar salt. Strains could not be distinguished using biochemical tests. There was no change in hydrophobicity following re-isolation of the bacteria from experimentally infected rainbow trout, Salmo gairdneri .     

The correlation between surface hydrophobicity and adherence of Bifidobacterium strains from centenarians' faeces

To develop food-grade bifidobacteria micro-ecologics, screening for Bifidobacteria strains which can adhere to intestinal epithelial cells was finished. Twenty-three bifidobacterial strains tested were isolated from centenarians in Bama country, the fifth long-lived district in the world. Surface hydrophobicity and adherence capability to intestinal epithelial cells in vitro of bifidobacteria were simultaneously investigated for the first time. It has been demonstrated that all the strains exhibited adhesive properties to some extent using intestinal Caco-2 cell line in in vitro model. It could be conclude that the higher hydrophobic strains the stronger adhesive capability. The highest value of hydrophobicity (37.24+/-1.45% and 32.06+/-1.21%) was obtained for strains H-10 and I-6, respectively; correspondingly, the strongest adherence ability (49.47+/-4.88/cell and 47.33+/-2.72/cell) was achieved, respectively. Correlation between surface hydrophobicity and adherence ability of different Bifidobacterium strains including polynomial regression equation (R2=0.78) had been achieved. The present study provided a liable and effective method for screening bifidobacteria with the ability to adhere to intestinal epithelial cells.     

Investigation of the relationship between cell surface hydrophobicity and demulsifying capability of biodemulsifier-producing bacteria

Background

Cell surface hydrophobicity (CSH) is one of the key physicochemical features of biodemulsifier-producing bacteria that influence their demulsification capability maintenance in petroleum contaminated environments.

Methods

In present study, biodemulsifier-producing bacteria were isolated from petroleum contaminated environments using different isolation media and the correlation between their CSH and demulsifying ability was investigated. The demulsifying ability of isolates was measured through demulsification tests on water in kerosene emulsions. The microbial adhesion to the hydrocarbon (MATH) assay was used to denote their CSH.

Results

The evaluation of CSH showed that majority of biodemulsifier producing bacteria have high CSH which indicating a positive correlation between CSH and demulsifying capability.

Conclusions

According to these results it can be concluded that CSH can be used as an indicator for assessment of biodemulsifier-producing bacteria and screening of new isolates for their biodemulsifier production.

     

Dynamic cell surface hydrophobicity of Lactobacillus strains with and without surface layer proteins

Variations in surface hydrophobicity of six Lactobacillus strains with and without an S-layer upon changes in ionic strength are derived from contact angle measurements with low- and high-ionic-strength aqueous solutions. Cell surface hydrophobicity changed in response to changes in ionic strength in three out of the six strains, offering these strains a versatile mechanism to adhere to different surfaces. The dynamic behavior of the cell surface hydrophobicity could be confirmed for two selected strains by measuring the interaction force between hydrophobic and hydrophilic tips with use of atomic force microscopy.     

A T cell activity that enhances polyclonal IgE production and its inhibition by interferon-gamma

The addition of concanavalin A-stimulated supernatants of the helper T cell clone, D9.1, to cultures of lipopolysaccharide (LPS)-stimulated T-depleted mouse spleen cells caused more than a 100-fold increase in immunoglobulin (Ig) E production. These supernatants cause a 10-fold to 15-fold increase in IgG1, a fivefold to 10-fold increase in IgA, and a fivefold to 10-fold decrease in IgG3. These effects are optimal when the supernatants are added 1 to 2 days after stimulation with LPS. Cells from mouse strains that normally give little or no IgE response in vivo give normal IgE levels in response to LPS plus the supernatant of Concanavalin A-stimulated D9.1 cells in vitro. The enhancement of both IgE and IgG1 can be completely inhibited by relatively low concentrations of interferon-gamma (IFN-gamma). Both the IgE-enhancing activity and IFN-gamma act directly upon purified B cells.     

Chaperone-like activity and surface hydrophobicity of 70S ribosome

Allergen from the house dust mite (Dermatophagoides sp.) is a major trigger factor of allergic disorders, and its characterization is crucial for the development of specific diagnosis or immunotherapy. Here we report the identification of a novel dust mite (Dermatophagoides farinae) antigen whose primary structure belongs to the gelsolin family, a group of actin cytoskeleton-regulatory proteins. Isolated mite cDNA, termed Der f 16, encodes 480 amino acids comprising a four-repeated gelsolin-like segmental structure, which is not seen in conventional gelsolin family members. Enzyme immunoassay indicated that recombinant Der f 16 protein, prepared using an Escherichia coli expression system, bound IgE from mite-allergic patients at 47% (8/17) frequency. This is the first evidence that the gelsolin family represents a new class of allergen recognizable by atopic patient IgE.     

Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 cell surface hydrophobicity and survival of the cells under adverse environmental conditions

Changes in the cell surface hydrophobicity (CSH) of probiotic bacteria Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 and the survival of these cells were examined in response to varied cultivation conditions and adverse environmental conditions. An inverse linear relationship (P < 0.01) was detected between the CSH of intact L. acidophilus La5 and B. lactis Bb12 and survival of cells subjected to subsequent freezing/thawing, long-term storage or exposure to mineral and bile acids. The observed relationships were supported by significant correlations between the CSH and changes in composition of the cell envelopes (proteins, lipids and carbohydrates) of L. acidophilus La5 and B. lactis Bb12 examined using FT-IR spectroscopy and conventional biochemical analysis methods. The results also suggest that the estimates of hydrophobicity, being a generalized characteristic of cell surfaces, are important parameters to predict the ability of intact probiotic bacteria to endure extreme environments and therefore should be monitored during cultivation. A defined balance of cell components, which can be characterized by the reduced CSH values, apparently helps to ensure the resistance, improved viability and hence the overall probiotic properties of bacteria.     

Hepatitis C virus inhibits cell surface expression of HLA-DR, prevents dendritic cell maturation, and induces interleukin-10 production

Hepatitis C virus (HCV) chronic infection is characterized by low-level or undetectable cellular immune responses against HCV antigens. HCV proteins have been shown to affect various intracellular events and modulate immune responses, although the precise mechanisms used to mediate these effects are not fully understood. In this study, we have examined the effect of HCV proteins on the modulation of major histocompatibility complex (MHC) class II expression and other functions important for antigen presentation in humans. Expression of an HCV(1-2962) genomic clone (HCV-FL) in human fibrosarcoma cells (HT1080) inhibited gamma interferon (IFN-gamma)-induced upregulation of human leukocyte antigen-DR (HLA-DR) cell surface expression. Furthermore, inhibition of promoter activities of MHC class II transactivator (CIITA), IFN-gamma-activated site (GAS), and HLA-DR was observed in IFN-gamma-inducible HT1080 cells expressing HCV-FL by in vitro reporter assays. Exposure of human monocyte-derived dendritic cells (DCs) to cell culture-grown HCV (HCVcc) genotype 1a (clone H77) or 2a (clone JFH1) significantly inhibited DC maturation and was associated with the production of IL-10. Furthermore, DCs exposed to HCVcc were impaired in their functional ability to stimulate antigen-specific CD4-positive (CD4(+)) and CD8(+) T-cell responses. Taken together, our results indicated that HCV can have direct and/or indirect inhibitory effects on antigen-presenting cells, resulting in reduction of antigen-specific T-cell activation. These effects may account for or contribute to the low overall level of immunogenicity of HCV observed in chronically infected patients.     

Cell surface components of Streptococcus sanguis: relationship to aggregation, adherence, and hydrophobicity.

Cell surfaces of aggregation, adherence, and hydrophilic variants of Streptococcus sanguis were compared with cell surfaces of the parent strain with regard to their protein and antigenic constituents. Cell surface molecules were released by digestion with mutanolysin. Extraction with sodium dodecyl sulfate (SDS) urea, lithium diiodosalicylate, and boiling water did not solubilize any material which stained with AgNO3 in an SDS-polyacrylamide gel electrophoresis gel. The parent organism S. sanguis 12, which aggregates in saliva, adheres to saliva-coated hydroxyapatite and is hydrophobic, was found to possess a prominently staining 160,000 molecular weight (MW) protein. This protein was almost completely absent from strain 12na, a hydrophobic nonaggregating variant, and was completely absent from the hydrophilic nonaggregating strain 12L. Trypsinization of strain 12 resulted in the coincident loss of the 160,000-MW protein and the ability to aggregate in saliva. Trypsin treatment reduced but did not eliminate the hydrophobic character of the cells. Boiling destroyed their ability to aggregate, but did not alter their hydrophobicity. Cell wall digests of strain 12 contained a number of proteins which were absent from strains 12na and 12L. Mutanolysin digests of cell walls of the hydrophilic strains contained almost no material that was visible in a silver-stained SDS-polyacrylamide gel electrophoresis gel. Culture supernatants contained a number of proteins which were immunologically cross-reactive with cell surface proteins. The hydrophilic organisms released a number of 60,000- to 90,000-MW proteins not seen in culture supernatants from the parent strain.     

Cell surface hydrophobicity and slime production of Staphylococcus epidermidis Brazilian isolates

The cell surface hydrophobicity of 60 isolates and three reference strains of Staphylococcus epidermidis was assayed by means of bacterial aggregation in liquid broth, phosphate-buffered saline, and in ammonium sulfate, as well as by affinity of the bacteria to n-hexadecane and polystyrene surfaces. In order to better characterize the isolates, the influence of bacterial growth time and enzyme treatment on cell hydrophobicity and the analysis of the slime production were also investigated. The strains presented the following profiles when assayed by the ammonium sulfate aggregation test (SAT): SAT < 1M, SAT 1M - <2M, SAT 2M - <4M, and SAT >or=4M. When SAT < 1M, the strains showed positive results for most of the cell surface hydrophobicity tests. None of the strains belonging to the groups with SAT >or= 1M showed spontaneous aggregation (SA), auto-aggregation (AA), or glass adherence, albeit 32 (62.7%) strains were polystyrene adherent and 42 (82.3%) presented weak adherence to n-hexadecane (>20%). The best correlation of the results was found among the AA and glass adherence tests (100%), followed by SA/ glass adherence (98%) and SA/ AA test (98%). The polystyrene adherence test and microbial adherence to n-hexadecane test (MATH) showed 78% correlation. Proteinase K treatment reduced bacterial adherence to polystyrene, but did not influence the SAT values. Three distinct groups of strains were distinguished by the polystyrene micromethod and glass tube adherence assay: 0.0-0.4 O.D. group, including non-glass adherent isolates; 0.5-0.7 O.D. group, including strains with variable profiles (adherent or non-adherent); and 0.8-1.3 O.D. group, composed of glass-adherent strains. Evaluation by a single method seemed not to reliably determine the surface hydrophobicity characteristics of S. epidermidis clinical isolates. Auto-aggregation properties of the strains that adhered to glass seemed related to slime expression, rather than cell surface hydrophobicity. Data also suggested involvement of protein components in adherence to polystyrene, but not in auto-aggregation properties assayed by SAT.     

Surface structures, haemagglutination and cell surface hydrophobicity of Bacteroides fragilis strains.

Nineteen strains of Bacteroides fragilis were examined by negative staining for surface structures. One strain (ATCC 23745) possessed peritrichous fibrils, 16 strains carried peritrichous fimbriae and two strains carried no surface structures. The fimbriae had a diameter of 2.1 +/- 0.25 nm and appeared to be 'curly'. Only a small proportion (4 to 41%, depending on the strain) of cells in a population carried fimbriae or fibrils. Strain A312 Showed phase variation of fimbriae as expression of fimbriae was repressed at 20 degrees C and in early exponential phase at 37 degrees C. The fibrils on strain ATCC 23745 did not exhibit phase variation in response to changes in incubation temperature, growth phase or growth in two different media. Capsules were demonstrated by the Indian ink method on 18 of the 19 strains, varying in size from strain to strain and within the same population. Cultures often contained both capsulate and noncapsulate cells. All strains possessed an electron dense ruthenium red staining layer between 7.9 and 23.9 nm in width attached to the outer membrane. Cell surface hydrophobicity quantified by the hexadecane partition assay gave low values ranging from 6.6 to 52.1%. Only a few strains were able to haemagglutinate and these were only weakly active. There was no correlation between cell surface hydrophobicity, haemagglutinating activity and surface structures.     

Increased cell surface hydrophobicity of a Serratia marcescens NS 38 mutant lacking wetting activity.

The cell surface hydrophobicity of Serratia marcescens appears to be an important factor in its adhesion to and colonization of various interfaces. The cell surface components responsible for mediating the hydrophobicity of S. marcescens have not been completely elucidated, but may include prodigiosin and other factors. In the present report we have investigated the potential role of serratamolide, an amphipathic aminolipid present on the surfaces of certain S. marcescens strains, in modulating cell surface hydrophobicity. The hydrophobic properties of a serratamolide-producing strain (NS 38) were compared with those of a serratamolide-deficient mutant (NS 38-9) by monitoring the kinetics of adhesion to hexadecane. Serratamolide production was monitored by thin-layer chromatography and the wetting activity of washed-cell suspensions on polystyrene. Wild-type NS 38 cells were far less hydrophobic than the serratamolide-deficient mutant cells were; the removal coefficients were 48 min-1 for the mutant, as compared with only 18 min-1 for the wild type. The data suggest that the presence of serratamolide on S. marcescens cells results in a reduction in hydrophobicity, presumably by blocking hydrophobic sites on the cell surface.     

Distribution of EPS and cell surface hydrophobicity in aerobic granules

This study described the distribution of extracellular polysaccharides (EPS) and hydrophobicity in aerobic granule as well as the essential role of EPS in maintaining the stable structure of aerobic granules. Aerobic granules showed a heterogeneous structure, which had an outer shell with high biomass density and an inner core having a relatively low biomass density. Results showed that the outer shell of aerobic granule was composed of poorly soluble and noneasily biodegradable EPS, whereas its core part was filled with readily soluble and biodegradable EPS. It was further found that the shell of aerobic granule exhibited a higher hydrophobicity than the core of granule. The insoluble EPS present in the granule shell would play a protective role with respect to the structure stability and integrity of aerobic granules.     

Influence of temperature on biofilm formation by Listeria monocytogenes on various food-contact surfaces: relationship with motility and cell surface hydrophobicity

Aims:  To assess the ability of Listeria monocytogenes to form biofilm on different food-contact surfaces with regard to different temperatures, cellular hydrophobicity and motility.
Methods and Results:  Forty-four L. monocytogenes strains from food and food environment were tested for biofilm formation by crystal violet staining. Biofilm levels were significantly higher on glass at 4, 12 and 22°C, as compared with polystyrene and stainless steel. At 37°C, L. monocytogenes produced biofilm at significantly higher levels on glass and stainless steel, as compared with polystyrene. Hydrophobicity was significantly ( P  < 0·05) higher at 37°C than at 4, 12 and 22°C. Thirty (68·2%) of 44 strains tested showed swimming at 22°C and 4 (9·1%) of those were also motile at 12°C. No correlation was observed between swimming and biofilm production.
Conclusions:  L. monocytogenes can adhere to and form biofilms on food-processing surfaces. Biofilm formation is significantly influenced by temperature, probably modifying cell surface hydrophobicity.
Significance and Impacts of the Study:  Biofilm formation creates major problems in the food industry because it may represent an important source of food contamination. Our results are therefore important in finding ways to prevent contamination because they contribute to a better understanding on how L. monocytogenes can establish biofilms in food industry and therefore survive in the processing environment.     

Lymphokine release, suppressor cell generation, cell surface markers, and cytotoxic activity in cancer patients receiving natural interleukin-2

We monitored patients treated for 5 days with continuous infusion of increasing doses (3 to 6 x 10(6) U/d) of natural interleukin-2 (IL-2). CD16+, CD25+, and CD56+ cells increased after treatment. Plasma tumor necrosis factor-alpha (TNF-alpha) levels, but not interferon-gamma (IFN-gamma) levels, increased during IL-2 treatment, but spontaneous and IL-2-stimulated TNF-alpha secretion in vitro remained abnormally low. However, mitogen-stimulated TNF-alpha release was normal. Mitogen-stimulated, but not IL-2-stimulated, IFN-gamma release was strongly depressed. Low spontaneous and IL-2-stimulated cytotoxicity on K562 or Daudi increased after treatment. Low suppressor cell generation also normalized after treatment. This appears to be the first reported study of immunologic monitoring of cancer patients treated with natural rather than recombinant IL-2.     

Assessment of proliferating cell nuclear antigen and its relationship with proinflammatory cytokines and parameters of disease activity in multiple myeloma patients

Multiple myeloma (MM) is a malignant plasma cell disease. Several proinflammatory cytokines produced by malignant plasma cells and bone marrow (BM) stromal cells are involved in the pathogenesis of the disease. We evaluated serum levels of the proinflammatory cytokines Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-1α), in MM patients before treatment, and determined its significance in tumor progression. We also analyzed the correlation between measured parameters with proliferating cell nuclear antigen (PCNA). Forty-four MM patients and 20 healthy controls were studied. Serum levels of the proinflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA), whereas PCNA value in the BM was determined by immunohistochemistry staining. The mean concentrations of the measured cytokines were significantly different among the three stages of disease, with higher values in advanced disease stage. Furthermore, patients with MM had significantly higher serum levels of the measured cytokines than in controls. A positive correlation was found between IL-6 with IL-1β, IL-8 and MIP-1α. Similarly, IL-8 and MIP-1α were positively correlated with markers of disease activity such as β2 microglobulin and LDH. The proliferation index, determined by PCNA immunostaining, was higher in advanced disease stage. Furthermore PCNA value correlated significantly with β2 microglobulin, LDH and the levels of the measured cytokines. Our results showed that the proliferative activity, as measured with PCNA, increases in parallel with disease stage. The positive correlation between PCNA and other measured mediators supports the involvement of these factors in the biology of myeloma cell growth and can be used as markers of disease activity and as possible therapeutic targets.     

Increased cell surface hydrophobicity associated with possession of an additional surface protein by Aeromonas salmonicida

Abstract The cell surface of strains of Aeromonas salmonicida possessing an additional surface protein (A-protein) was shown to be more hydrophobic than strains devoid of this protein, using the techniques of phase partitioning, agglutination in the presence of ammonium sulphate and hydrophobic interaction chromatography.