Foam separation of <i>Escherichia Coli</i> with a cationic surfactant

Grieves, Robert B.; Wang, Shing-Ling

doi:10.1002/bit.260080302

Cited by 43 publications

(12 citation statements)

References 11 publications

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“…The adsorbed polymer may increase cell surface hydrophobicity by reducing the polar effects of negatively charged surface components. Concom- (5), and flocculation of yeast cells (7). This phenomenon may be due to inhibition by unadsorbed polycations of cell-cell interaction.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers

1990

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Polycationic polymers have been noted for their effects in promoting cell adhesion to various surfaces, but previous studies have failed to describe a mechanism dealing with this type of adhesion. In the present study, three polycationic polymers (chitosan, poly-L-lysine, and lysozyme) were tested for their effects on microbial hydrophobicity, as determined by adhesion to hydrocarbon and polystyrene. Test strains (Escherichia coli, Candida albicans, and a nonhydrophobic mutant, MR-481, derived from Acinetobacter calcoaceticus RAG-1) were vortexed with hexadecane in the presence of the various polycations, and the extent of adhesion was measured turbidimetricaily. Adhesion of all three test strains rose from near zero values to over 90% in the presence of low concentrations of chitosan (125 to 250 ,ug/ml). Adhesion occurred by adsorption of chitosan directly to the cell surface, since E. coli cells preincubated in the presence of the polymer were highly adherent, whereas hexadecane droplets pretreated with chitosan were subsequently unable to bind untreated cells. Inorganic cations (Na+, Mg2+) inhibited the chitosan-mediated adhesion of E. coli to hexadecane, presumably by interfering with the electrostatic interactions responsible for adsorption of the polymer to the bacterial surface. Chitosan similarly promoted E. coli adhesion to polystyrene at concentrations slightly higher than those which mediated adhesion to hexadecane. Poly-L-lysine also promoted microbial adhesion to hexadecane, although at concentrations somewhat higher than those observed for chitosan. In order to study the effect of the cationic protein lysozyme, adhesion was studied at 0°C (to prevent enzymatic activity), using n-octane as the test hydrocarbon. Adhesion of E. coli increased by 70% in the presence of 80 ,ug of lysozyme per ml. When the negatively charged carboxylate residues on the E. coli cell surface were substituted for positively charged ammonium groups, the resulting cells became highly hydrophobic, even in the absence of polycations. The observed "hydrophobicity" of the microbial cells in the presence of polycations is thus probably due to a loss of surface electronegativity. The data suggest that enhancement of hydrophobicity by polycationic polymers is a general phenomenon.

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Section: Discussionmentioning

confidence: 99%

Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers

1990

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“…In this study the incorporation of foam fractionation into the basic fermenter design using the gas entrainment principle removed a large proportion of the wild-type cells from the fermenter. Foam fractionation has been reported to concentrate bacteria cells 106-fold (Grieves & Wang, 1966); however, total counts of this organism showed 103-fold concentration after 2 h operation.…”

Section: Ep Analysismentioning

confidence: 93%

Selection of Attachment Mutants during the Continuous Culture of Pseudomonas fluorescens and Relationship between Attachment Ability and Surface Composition

Fletcher

Ellwood

1983

Microbiology

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A strain of PseudomonasJIuorescens that had been isolated from a freshwater source on a plastic substratum was grown in continuous culture in minimal medium. The 'adsubble' process (adsorptive bubble separation process) was found to foam-fractionate wild-type cells from the fermenter during flow conditions. This selection pressure favoured the enrichment of two major classes of mutant, both having cell surface characteristics fundamentally different from the wild-type. The wild-type produced very little extracellular polysaccharide, whereas a 'mucoid' mutant, found predominantly in the aqueous-phase, produced an alginate exopolymer. The second class of mutant was isolated from the walls of the fermenter and, like the wild-type, produced little exopolymer. This mutant, with crenated colony morphology, showed increased attachment to solid surfaces compared to the wild-type and mucoid cells when assayed for attachment to polystyrene surfaces for 2 h. Outer-membrane protein, lipopolysaccharides and exopolysaccharides of the wild-type and both mutants were analysed. The results demonstrate the role of cell surface characteristics in the adaptability of the organism to micro-environments such as a solid/liquid or air/liquid interface or the aqueous phase.

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“…The typical aqueous environment and the surface activity of many bioproducts make the extension of the use of flotation to biotechnology a logical step (Evans et al, 1970;Kalischewski et al, 1979;Kolsaridu et al, 1983;Vardar-Sukan, 1988). There was an initial broad application of flotation in biotechnology during the 1930s, but it was eventually restricted to waste treatment, probably due to the fear of loss of biological activity (Bishop, 1978;Dognon and Dumontet, 1941;Gehle and Schiirgel, 1984a;Golab and Smith, 1990;Grieves and Wang, 1966;LeGloahec and Herter, 1938;Gaudin, 1957;Rubin, 1968;Rubin et al, 1966;Turrall et al, 1943). Recently, investigators revived the successful application of flotation in biotechnology.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Column Flotation in the Downstream Processing of Fermentation Products: Recovery of a Genetically Engineered α‐Amylase

Miranda

Berglund

1993

Biotechnology Progress

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Flotation is a simple, inexpensive, and versatile unit operation with a largely unexplored potential in biotechnology. There is a general lack of research concerning biotechnological applications in this area, especially in the recovery of fermentation products. Moreover, the few reports in the literature do not consider the modern concept of column flotation as practiced in the mineral industry. We report herein the application of column flotation for the recovery of a Bacillus stearothermophilus alpha-amylase expressed in Escherichia coli by the use of a food-grade polymer, (hydroxypropyl)methylcellulose (HPMC), and ammonium sulfate. First, the enzyme was removed from the liquid phase by partition to a salted-out HPMC phase. The enzyme-containing polymer flocs were then floated from the liquid. Recovery of active enzyme was as high as 90%, with throughput as high as 94 m3/(h.m2). The floatability of the enzyme from a periplasmic extract was higher than extracellular enzyme in the broth due to the presence of depressors of molecular weight lower than 10,000 in the broth.

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Foam separation of Escherichia Coli with a cationic surfactant

Cited by 43 publications

References 11 publications

Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers

Mechanism of enhancement of microbial cell hydrophobicity by cationic polymers

Selection of Attachment Mutants during the Continuous Culture of Pseudomonas fluorescens and Relationship between Attachment Ability and Surface Composition

Evaluation of Column Flotation in the Downstream Processing of Fermentation Products: Recovery of a Genetically Engineered α‐Amylase

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