Cell surface and exopolymer characterization of laboratory stabilized activated sludge from a beverage bottling plant

2001 ◽  
Vol 43 (6) ◽  
pp. 175-184 ◽  
Author(s):  
S. M. Boyette ◽  
J. M. Lovett ◽  
W. G. Gaboda ◽  
J. A. Soares
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Surface Charge ◽  
Electrophoretic Mobility ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Food Sources ◽  
Colloid Titration ◽  
High Concentrations

Fermentor-stabilized activated sludge from an industrial beverage bottling plant was grown on three different food sources: normal plant wastewater, plant wastewater containing high sucrose concentrations, and a synthetic glucose-based feed stock. Surface charge, hydrophobicity, and exopolysaccharide composition were measured on the stabilized bacterial flocs. Cell surface charge was measured by electrophoretic mobility, dye exchange titration, and a standard colloid titration, while cell hydrophobicity was determined using the bacterial adhesion to hydrocarbons (BATH) test. Exopolysaccharide profiles were determined by measuring concentrations of glucose, galactose, mannose, glucuronic, and galacturonic acids in digested exopolymer extractions using HPLC. Changes in the physical surface properties of the bacteria and the chemical composition of the extracted exopolymers were correlated with differences in the three food sources. Cell surface hydrophobicity was similar for cultures grown on different plant wastewaters, while the culture grown on synthetic food produced less floc hydrophobicity. Electrophoretic mobility measurements, charge titrations, and dye exchange titrations showed different total surface charge as well as varying charge availability. Additionally, total surface charge and total exopolysaccharide concentrations appeared less dependent on food source than the food-to-mass ratio. High concentrations of biodegradable food produced dispersed growth and high concentrations of exopolysaccharides that contributed to poor settling.

scholarly journals Characterization of Monolaurin Resistance in Enterococcus faecalis

2007 ◽  
Vol 73 (17) ◽  
pp. 5507-5515 ◽  
Author(s):  
Muriel Dufour ◽  
Janet M. Manson ◽  
Philip J. Bremer ◽  
Jean-Pierre Dufour ◽  
Gregory M. Cook ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Enterococcus Faecalis ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Wall Structure ◽  
Transmission Electron ◽  
Serious Infections ◽  
Autolytic Activity

ABSTRACT There is increasing concern regarding the presence of vancomycin-resistant enterococci in domestically farmed animals, which may act as reservoirs and vehicles of transmission for drug-resistant enterococci to humans, resulting in serious infections. In order to assess the potential for the use of monolaurin as a food preservative, it is important to understand both its target and potential mechanisms of resistance. A Tn917 mutant library of Enterococcus faecalis AR01/DGVS was screened for resistance (MIC, >100 μg/ml) to monolaurin. Three mutants were identified as resistant to monolaurin and were designated DGRM2, DGRM5, and DGRM12. The gene interrupted in all three mutants was identified as traB, which encodes an E. faecalis pheromone shutdown protein and whose complementation in trans restored monolaurin sensitivity in all three mutants. DGRM2 was selected for further characterization. E. faecalis DGRM2 showed increased resistance to gentamicin and chloramphenicol (inhibitors of protein synthesis), while no difference in the MIC was observed with the cell wall-active antibiotics penicillin and vancomycin. E. faecalis AR01/DGVS and DGRM2 were shown to have similar rates (30% cell lysis after 4 h) of cell autolytic activity when activated by monolaurin. Differences in cell surface hydrophobicity were observed between the wild type and the mutant, with the cell surface of the parent strain being significantly more hydrophobic. Analysis of the cell wall structure of DGRM2 by transmission electron microscopy revealed an increase in the apparent cell wall thickness and contraction of its cytoplasm. Taken together, these results suggest that the increased resistance of DGRM2 was due to a change in cell surface hydrophobicity, consequently limiting the diffusion of monolaurin to a potential target in the cytoplasmic membrane and/or cytoplasm of E. faecalis.

scholarly journals Effects of Hydrophobic and Electrostatic Cell Surface Properties of Bacteria on Feeding Rates of Heterotrophic Nanoflagellates

2001 ◽  
Vol 67 (2) ◽  
pp. 814-820 ◽  
Author(s):  
Carsten Matz ◽  
Klaus Jürgens
Keyword(s):  
Cell Surface ◽  
Surface Charge ◽  
Food Selection ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Common Species ◽  
Electrostatic Charge ◽  
Heterotrophic Nanoflagellates ◽  
Feeding Rates ◽  
Protozoan Grazing

ABSTRACT The influence of cell surface hydrophobicity and electrostatic charge of bacteria on grazing rates of three common species of interception-feeding nanoflagellates was examined. The hydrophobicity of bacteria isolated from freshwater plankton was assessed by using two different methods (bacterial adhesion to hydrocarbon and hydrophobic interaction chromatography). The electrostatic charge of the cell surface (measured as zeta potential) was analyzed by microelectrophoresis. Bacterial ingestion rates were determined by enumerating bacteria in food vacuoles by immunofluorescence labelling via strain-specific antibodies. Feeding rates varied about twofold for each flagellate species but showed no significant dependence on prey hydrophobicity or surface charge. Further evidence was provided by an experiment involving flagellate grazing on complex bacterial communities in a two-stage continuous culture system. The hydrophobicity values of bacteria that survived protozoan grazing were variable, but the bacteria did not tend to become more hydrophilic. We concluded that variability in bacterial cell hydrophobicity and variability in surface charge do not severely affect uptake rates of suspended bacteria or food selection by interception-feeding flagellates.

scholarly journals Heterologous Inducible Expression ofEnterococcus faecalis pCF10 Aggregation Substance Asc10 inLactococcus lactis and Streptococcus gordonii Contributes to Cell Hydrophobicity and Adhesion to Fibrin

2000 ◽  
Vol 182 (8) ◽  
pp. 2299-2306 ◽  
Author(s):  
Helmut Hirt ◽  
Stanley L. Erlandsen ◽  
Gary M. Dunny
Keyword(s):  
Cell Surface ◽  
Cell Surface Hydrophobicity ◽  
Regulatory System ◽  
Surface Hydrophobicity ◽  
Bacterial Cells ◽  
Streptococcus Gordonii ◽  
Cell Surfaces ◽  
Gene Encoding ◽  
Aggregation Substance

ABSTRACT Aggregation substance proteins encoded by the sex pheromone plasmid family of Enterococcus faecalis have been shown previously to contribute to the formation of a stable mating complex between donor and recipient cells and have been implicated in the virulence of this increasingly important nosocomial pathogen. In an effort to characterize the protein further, prgB, the gene encoding the aggregation substance Asc10 on pCF10, was cloned in a vector containing the nisin-inducible nisA promoter and its two-component regulatory system. Expression of aggregation substance after nisin addition to cultures of E. faecalis and the heterologous bacteria Lactococcus lactis andStreptococcus gordonii was demonstrated. Electron microscopy revealed that Asc10 was presented on the cell surfaces ofE. faecalis and L. lactis but not on that ofS. gordonii. The protein was also found in the cell culture supernatants of all three species. Characterization of Asc10 on the cell surfaces of E. faecalis and L. lactisrevealed a significant increase in cell surface hydrophobicity upon expression of the protein. Heterologous expression of Asc10 on L. lactis also allowed the recognition of its binding ligand (EBS) on the enterococcal cell surface, as indicated by increased transfer of a conjugative transposon. We also found that adhesion of Asc10-expressing bacterial cells to fibrin was elevated, consistent with a role for the protein in the pathogenesis of enterococcal endocarditis. The data demonstrate that Asc10 expressed under the control of the nisA promoter in heterologous species will be an useful tool in the detailed characterization of this important enterococcal conjugation protein and virulence factor.

Relationship of Cell Surface Charge and Hydrophobicity to Strength of Attachment of Bacteria to Cantaloupe Rind†

2002 ◽  
Vol 65 (7) ◽  
pp. 1093-1099 ◽  
Author(s):  
DIKE O. UKUKU ◽  
WILLIAM F. FETT
Keyword(s):  
Cell Surface ◽  
Surface Charge ◽  
Cell Surface Hydrophobicity ◽  
Hydrophobic Interaction Chromatography ◽  
Surface Hydrophobicity ◽  
Bacterial Attachment ◽  
Wash Water ◽  
Bacterial Surface ◽  
E Coli ◽  
Salmonella Infections

The cantaloupe melon has been associated with outbreaks of Salmonella infections. It is suspected that bacterial surface charge and hydrophobicity may affect bacterial attachment and complicate bacterial detachment from cantaloupe surfaces. The surface charge and hydrophobicity of strains of Salmonella, Escherichia coli (O157:H7 and non-O157:H7), and Listeria monocytogenes were determined by electrostatic and hydrophobic interaction chromatography, respectively. Initial bacterial attachment to cantaloupe surfaces and the ability of bacteria to resist removal by washing with water were compared with surface charge and hydrophobicity. Whole cantaloupes were submerged in inocula containing individual strains or in cocktails containing Salmonella, E. coli, and L. monocytogenes, either as a mixture of strains containing all three genera or as a mixture of strains belonging to a single genus, for 10 min. Inoculated cantaloupes were dried for 1 h in a biosafety cabinet and then stored for up to 7 days at 4°C. Inoculated melons were washed with water, and bacteria still attached to the melon surface, as well as those in the wash water, were enumerated. Initial bacterial attachment was highest for individual strains of E. coli and lowest for L. monocytogenes, but Salmonella exhibited the strongest attachment on days 0, 3, and 7. When mixed-genus cocktails were used, the relative degrees of attachment of the three genera ware altered. The attachment of Salmonella strains was the strongest, but the attachment of E. coli was more extensive than that of L. monocytogenes on days 0, 3, and 7. There was a linear correlation between bacterial cell surface hydrophobicity (r2 = 0.767), negative charge (r2 = 0.738), and positive charge (r2 = 0.724) and the strength of bacterial attachment to cantaloupe surfaces.

Influence of oxygen limitation on the cell surface properties of bacteria from activated sludge

1998 ◽  
Vol 37 (4-5) ◽  
pp. 349-352 ◽  
Author(s):  
R. Palmgren ◽  
F. Jorand ◽  
P. H. Nielsen ◽  
J. C. Block
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Surface Properties ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Growth Conditions ◽  
Oxygen Limitation ◽  
Cell Surface Properties ◽  
Number Of Factors ◽  
Math Test

Cell surface hydrophobicity is believed to be important to flocculation in activated sludge and biofilm systems. Optimization of these processes includes changes in the growth conditions of the bacteria. A number of factors influence cell surface hydrophobicity. The influence of oxygen on the cell surface hydrophobicity of 4 bacteria isolated from activated sludge was tested. The bacteria were grown in batch cultures with and without oxygen limitation. It was found that oxygen limitation generally caused a lowering of the cell surface hydrophobicity. The study also showed that there are many difficulties in measuring cell surface hydrophobicity since other cell surface properties, such as surface charge, influence the measurement methods. The MATH test was employed to establish how assay conditions influenced the results.

Cell-surface hydrophobicity and cell-surface charge of Azospirillum spp.

2006 ◽  
Vol 24 (2) ◽  
pp. 159-172 ◽  
Author(s):  
Thelma Castellanos ◽  
Felipe Ascencio ◽  
Yoav Bashan
Keyword(s):  
Cell Surface ◽  
Surface Charge ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Cell Surface Charge
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