XDLVO model Dotaz Zobrazit nápovědu
Acidothermophilic bacteria of the genus Alicyclobacillus are frequent contaminants of fruit-based products. This study is the first attempt to characterize the physico-chemical surface properties of two Alicyclobacillus sp. and quantify their adhesion disposition to model materials [diethylaminoethyl (DEAE), carboxyl- and octyl-modified magnetic beads] representing materials with different surface properties used in the food industry. An insight into the mechanism of adhesion was gained through comparison of experimental adhesion intensities with predictions of a colloidal interaction model (XDLVO). Experimental data (contact angles, zeta potentials, size) on interacting surfaces (cells and materials) were used as inputs into the XDLVO model. The results revealed that the most significant adhesion occurred at pH 3. Adhesion of both vegetative cells and spores of two Alicyclobacillus sp. to all materials studied was the most pronounced under acidic conditions, and adhesion was influenced mostly by electrostatic attractions. The most intensive adhesion of vegetative cells and spores at pH 3 was observed for DEAE followed by hydrophobic octyl and hydrophilic carboxyl surfaces. Overall, the lowest rate of adhesion between cells and model materials was observed at an alkaline pH. Consequently, prevention of adhesion should be based on the use of alkaline sanitizers and/or alkaline rinse water.
- Klíčová slova
- Alicyclobacillus sp., Cell adhesion, Model materials, Surface interaction, XDLVO model,
- MeSH
- Alicyclobacillus chemie fyziologie MeSH
- bakteriální adheze * MeSH
- koncentrace vodíkových iontů MeSH
- povrchové vlastnosti MeSH
- spory bakteriální chemie fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
Magnetic harvesting of microalgal biomass provides an attractive alternative to conventional methods. The approach to this issue has so far been pragmatic, focused mainly on finding cheap magnetic agents in combination with harvestable microalgae species. The aim of this work was to study experimentally and theoretically the mechanisms leading to cell-magnetic agent attachment/detachment using real experiments and predictions made by colloidal adhesion (XDLVO) model. Two types of well defined magnetic beads (MBs) carrying ion exchange functional groups (DEAE - diethylaminoethyl and PEI - polyethylenimine) were studied in connection with microalgae (Chlorella vulgaris). Optimal harvesting efficiencies (>90%) were found for DEAE and PEI MBs, while efficient detachment was achieved only for DEAE MBs (>90%). These findings were in accordance with the predictions by XDLVO model. Simultaneously there was found a discrepancy between the XDLVO prediction and the poor detachment of PEI MBs from microalgal surface. This can be ascribed to an additional interaction (probably covalent bonds) between PEI and algal surface, which the XDLVO model is unable to capture given by its non-covalent nature.
- Klíčová slova
- Cell adhesion, Magnetic beads, Microalgae, Surface interactions, XDLVO theory,
- MeSH
- biologické modely MeSH
- biomasa MeSH
- buněčná adheze MeSH
- Chlorella vulgaris izolace a purifikace fyziologie MeSH
- ethanolaminy chemie MeSH
- iontová výměna MeSH
- koloidy MeSH
- magnetické jevy MeSH
- magnetické nanočástice chemie MeSH
- mikrořasy izolace a purifikace fyziologie MeSH
- polyethylenimin chemie MeSH
- povrchové vlastnosti MeSH
- průmyslová mikrobiologie metody MeSH
- sladká voda mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- 2-diethylaminoethanol MeSH Prohlížeč
- ethanolaminy MeSH
- koloidy MeSH
- magnetické nanočástice MeSH
- polyethylenimin MeSH
Pythium oligandrum, a soil-born oomycete, is an effective biological control agent exhibiting antagonistic and parasitic activity against pathogenic fungi. This study is the first attempt to characterize its surface properties and to apply models of physicochemical interactions (thermodynamic, DLVO and XDLVO) to quantify its adhesion properties to a model material, represented by magnetic beads (MB). The predictions of interaction models were based on experimental data (contact angles, zeta potentials, size). Adhesion intensities (AI) were determined experimentally taking advantage of MB with different surface properties. The role of weak physicochemical interactions was estimated by comparing experimental AI with model predictions. The results revealed that the surface properties of the three Pythium spp. studied were very similar and fell within the range for hydrophilic microorganisms (ΔGTOT > 0) with a predominantly negative surface charge. The most reliable description of AI was obtained using the DLVO model, including Lifshitz-van der Waals and electrostatic interactions. The highest AI between Pythium spp. and all three MB was observed at pH 3, which was supported by the DLVO prediction. The greater agreement between the sphere-sphere geometric version of the DLVO model and experiment suggests that the surface protrusions of the oospores increase the efficiency of adhesion. The surface properties of the pathogenic fungi, characterized in this work, fell within the range defined by MB and therefore it can be expected that their physicochemical interactions with Pythium spp. will also be favourable.
- Klíčová slova
- (X)DLVO model, Adhesion, Model materials, Pythium species, Surface interaction, Thermodynamic model,
- Publikační typ
- časopisecké články MeSH
The main aim of this work was to determine the most appropriate materials for the installation of a water system according to the characteristics of the water that passes through it. To this end, we conducted an investigation of the effect of two types of water (SDW: sterile distilled water and STW: sterile tap water) on the properties of bacterial surfaces and the theoretical adhesion of two bacteria (Pseudomonas aeruginosa and Escherichia coli) on six plumbing materials. Contact angle measurements were used to determine the surface energies of bacteria and materials. XDLVO theory was used to estimate the interactions between bacteria and plumbing materials. The results showed that water had a clear impact on the electron donor character and the hydrophobicity of the bacterial surfaces. Also, the predictive adhesion showed that all tested materials could be colonized by P. aeruginosa and E. coli ([Formula: see text]<0). However, colonization became thermodynamically less favorable or unfavorable (increase in [Formula: see text] values) with SDW and STW, respectively. Finally, the results suggest that the choice of the most suitable material for a drinking water installation is related to the quality of the water itself.
One of the industrially important qualities of yeast is their ability to provide the cell-cell and cell-support interactions. This feature of yeast is responsible for technologically significant phenomena such as flocculation (brewing) and yeast biofilm formation (immobilization to supports), whereas these phenomena are time, environment, and strain dependent. Therefore, the goal of this work was to verify the possibility to predict and subsequently select yeast strains capable to colonize solid supports by using physicochemical adhesion models. Three different industrial yeast strains (Saccharomyces cerevisiae) were tested for their adhesion onto spent grain particles in the continuous gas-lift reactor. The cell adhesion energies were calculated, based on physicochemical characteristics of surfaces involved, according to three adhesion models (DLVO theory, thermodynamic approach, and extended DLVO theory). The role of physicochemical surface properties in the cell-cell and cell-support interactions was evaluated by comparing the computed predictions with experimental results. The best agreement between forecast and observation of the yeast adhesion to spent grains was achieved with the extended DLVO (XDLVO) theory, the most complex adhesion model applied in this study. Despite its relative comprehensiveness, the XDLVO theory does not take into account specific biochemical interactions. Consequently, additional understanding of the yeast adhesion mechanism was obtained by means of quantifying the expression of selected FLO genes. The presented approach provides tools to select the appropriately adhesive yeast strains and match them with solid supports of convenient surface properties in order to design immobilized biocatalysts exploitable in biotechnological processes.
- MeSH
- biotechnologie MeSH
- buněčná adheze MeSH
- flokulace MeSH
- fyzikální chemie MeSH
- imobilizované proteiny chemie MeSH
- lektiny vázající mannosu klasifikace genetika metabolismus MeSH
- molekulární sekvence - údaje MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- povrchové vlastnosti MeSH
- Saccharomyces cerevisiae - proteiny klasifikace genetika metabolismus MeSH
- Saccharomyces cerevisiae * genetika metabolismus MeSH
- sekvence nukleotidů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- FLO1 protein, S cerevisiae MeSH Prohlížeč
- imobilizované proteiny MeSH
- lektiny vázající mannosu MeSH
- Saccharomyces cerevisiae - proteiny MeSH
