Effect of low-concentration rhamnolipid on adsorption of Pseudomonas aeruginosa ATCC 9027 on hydrophilic and hydrophobic surfaces (original) (raw)
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Surface-Active Properties of Rhamnolipids From Pseudomonas Aeruginosa GS3
Journal of basic microbiology, 1997
Pseudomonas aeruginosa GS3 produced rhamnolipid biosurfactants during growth on carbohydrates, higher chain length n-alkanes and I-alkenes, petroleum crude oil and vegetable oils. With glucose as the substrate, maximum surfactant production (0.44 gfl) was observed during the stationary phase of growth. Partially purified rhamnolipids showed excellent surface-active properties in terms of reduction in the interfacial tension between them and a variety of hydrocarbons, hydrocarbon mixtures and vegetable oils and formation of stable emulsion.
Colloids and Surfaces B: Biointerfaces, 2007
The effect of rhamnolipid produced by a Pseudomonas aeruginosa strain on the aerobic degradation of granular organic substrate from kitchen waste by the bacterium was studied and compared with that of two synthetic surfactants, SDS and Triton X-100. The adsorption of rhamnolipid on the substrate, the surfactant-interfered adhesion of bacteria on the substrate as well as physicochemical and microbial conditions of the substrate during degradation were investigated. The adsorption isotherm of rhamnolipid on the substrate fit Freundlich law and its interactions with the substrate and bacteria weakened the adsorption of the bacteria on the substrate. The two synthetic surfactants, however, did not have such microbial effects. During degradation, rhamnolipid slowed down water evaporation in the substrate and significantly strengthened the dispersion of organic matter into the substrate water phase. The number of cells in the rhamnolipid treatment was higher than that in control and the remaining organic matter content in the substrates also had faster decreasing. SEM examination showed the on-site degradation of the substrate organic matter without rhamnolipid and the transfer of the degradation site in the presence of rhamnolipid. The results indicated that interference of rhamnolipid in the substrate matrix plays a potential role, physicochemically or microbially, on the degradation of the granular organic substrate. SDS and Triton X-100 may have the above physicochemical effects, but not so significant.
Bioadsorption characteristics of Pseudomonas aeruginosa PAOI
Journal of the Serbian Chemical Society, 2014
Biosorption of Cd(II) and Pb(II) ions from aqueous solution using lyophilized Pseudomonas aeruginosa PAO1 cells were observed under various experimental conditions. The effect of pH, initial metal concentration, equilibration time and temperature on bio-adsorption was investigated. The optimum pH value for Pb(II) adsorption was found to be 5.0, and for Cd(II) 5.0-6.0. The Pb(II) and Cd(II) bio-adsorption equilibrium were analyzed employing the Freundlich and Langmuir Models using nonlinear least-squares estimations. The experimental maximum uptake capacity of Pb(II) and Cd(II) was estimated to be 164 and 113 mg g -1 , respectively. For a kinetic study of the biosorptions, the pseudo second-order kinetic model was applied at various temperatures. The temperature had no significant effect on Pb(II) bio-adsorption. In case of Cd(II) bio-adsorption, the adsorbed amount decreased with increasing temperature.
Applied Microbiology and Biotechnology, 2011
The long-term influence of silicone oil 200 cSt (SO200) and 2, 2, 4, 4, 6, 8, on the cell surface hydrophobicity (CSH) of a hexanedegrading Pseudomonas aeruginosa strain and a toluenedegrading Pseudomonas putida strain was assessed in twophase partitioning bioreactors under batch and continuous operation. CSH was evaluated using a modified BATH method based on optical density (CSH OD ) and colonyforming unit (CSH CFU ) measurements. In the presence of HMN, P. aeruginosa turned hydrophobic over the time course as shown by the gradual increase in CSH OD (61± 1%) and CSH CFU (53±3%) under batch degradation and in CSH OD (49±0%) under continuous operation. However, P. putida turned hydrophobic only under continuous operation (CSH OD ¼ 28 AE 2%). On the other hand, no significant CSH enhancement was observed in both Pseudomonas strains in the presence of SO200. These results suggested that CSH is species, non-aqueous phase, and cultivation mode dependant, and an inducible property of bacteria. Maximum hexane elimination capacities increased by 2 and 3 in the presence of SO200 and HMN, respectively. Based on the absence of CSH in P. aeruginosa in the presence of SO200, the higher elimination capacities recorded were likely due to an improved hexane mass transfer (physical effect). However, in the presence of HMN, a direct hexane uptake from the non-aqueous phase (biological effect) might have also contributed to this enhancement.
Hydrophobicities and Electrostatic Behavior of Different Microorganisms
The surface properties of 7 different micro-organisms with their 14 different strains were examined. The contact angles of the micro-organism films were measured by a captive-bubble technique. Surface free energies were calculated from the contact angles. Hydrophobicities were also evaluated by adhesion to p-xylene. The zeta potentials and surface charges of the micro-organisms were measured using a zeta potential analyser system. The contact angles of the gram positive micro-organisms, gram negative micro-organisms and Candida ablicans were in the ranges 48-70°, 43.5-55°, and 69-75° respectively, while the corresponding surface free energies were in the ranges 44.9-60.4 erg.cm-2, 55.3-61.8 erg.cm-2 and 46.9-50.6 erg.cm-2 respectively. The p-xylene adhesions were in parallel to the hydrophobicities defined by the contat angles: 35.4-80.3%, 2.3-36.6%, and 67.3-86.2 for the gram positive bacteria, gram negative bacteria and Candida albicans yeasts respectively. The zeta potentials for...
FEMS Microbiology Letters, 2007
The partitioning of bacterial cells in a dual aqueous-solvent phase system leads to separation into 'hydrophilic' and hydrophobic functions. Sequential multistep partitioning, accompanied by successive enrichment, gives rise to several cycles of hydrophobic and hydrophilic cell populations which possess different cell-surface hydrophobicity characteristics. Characterization of the cell-surface hydrophobicity by several methods (salting-out aggregation test, bacterial adherence to hydrocarbon, polystyrene binding and hydrophobic interaction chromatography) was carried out. The cell-surface hydrophobicity varied in the order: hydrophilic fraction o parental strain o first cycle hydrophobic variant o second cycle hydrophobic variant o third cycle hydrophobic variant. Electron microscopy showed that the most hydrophobic variant was densely covered by hydrophobic structures -fimbriae -whereas the parental strain was covered by a mixture of surface structures. The hydrophilic variant was covered by an amorphous exopolymeric substance, which is a polysaccharide, shown by its reaction with Alcian blue.
Surfactants and the attachment of Pseudomonas aeruginosa to 3CR12 stainless steel and glass
Water SA, 2004
Five non-ionic and three anionic surfactants were evaluated using 4'6-diamidino-2-phenylidole (DAPI) staining, scanning electron microscopy (SEM) and spectrophotometry for their efficacy in preventing adhesion and removing Ps. aeruginosa attached to 3CR12 stainless steel coupons and glass. All the surfactants tested gave more than 90% inhibition of adhesion to the surfaces tested with no significant difference between the effectivity of the different anionic surfactants (p > 0.18) nor between the effectivity of the non-ionic surfactants (p > 0.16). The non-ionic and anionic surfactants resulted in more than 80% and 63% removal of attached Ps. aeruginosa cells, respectively. The non-ionic surfactants were significantly more effective in removing attached bacteria, than the anionic surfactants (p < 0.001). The prevention of attachment of Ps. aeruginosa cells to a glass surface, using the surfactants, was also monitored spectrophotometrically. There was no significant difference (p = 0.437) when comparing the DAPI-staining technique with spectrophotometric evaluations.
ACS Biomaterials Science & Engineering, 2017
We examined the effect of a crystalline layer of silica particles in the size range 0.5-4 µm on the adsorption and surface growth of Pseudomonas aeruginosa. Growth on these colloidal crystal monolayers (CCMs) was compared to growth on a flat plate of silica. All surfaces were coated with a thin film of silica to provide chemical uniformity of the different topographies. The results showed that the CCM reduces the density of colony forming units (CFU) on the solid by 99-99.9% when the suspension load was 10 3 CFU. We also examined the interaction between the CCM and either antibiotics or a chemically-bound antimicrobial. The addition of 20 µg/mL tobramycin after an initial 24 h growth period caused a further decrease in CFU counts of about 99-99.9% for all topographies. The percentage reduction as a result of the antibiotics was similar for all topographies, which suggested that there was no particular synergy between the topography and antibiotics. On the other hand, the additive nature of the two effects suggested promise for clinical studies: the large percentage reduction in CFU density on addition of the antibiotic to a flat surface was maintained on the topography, even starting from a much lower CFU density. A similar result was obtained for the combination of CCM and a covalently bound layer of antimicrobial polyallylamine hydrochloride (PAH). The PAH reduced the CFU and the CCM caused a further reduction; the two factors behaved approximately independently. Overall the CCM was found to be very effective at reducing the density of adsorbed P. aeruginosa, either with or without the additional reductions caused by antibiotics or surface-bound antimicrobials.
Physicochemical properties of bacterial surfaces
Biochemical Society Transactions, 1989
It was early recognized that certain bacteria, particularly encapsulated ones, evaded contact with phagocytes (Mudd et al., 1934), and thereby also avoided being ingested and killed by these cells. Moreover, certain bacteria are resistant not only to phagocytosis, but also to serum bactericidal systems, Abbreviations used: S. smooth; R, rough; LPS. lipopoly saccharide; PEG, polyethylene glycol; SlgA, secretory IgA; MS. rnannose-sensitive; GS, Gala I-4Gal-sensitive. I would like to thank Professor Lars Edebo for introducing me into the field of cell membrane biophysical research; Professor Edebo and a number of unnamed friends for fruitful co-operations. and Bertil Larsson in particular for excellent technical assistance. This research has been supported by the Swedish Medical Research Council (project no. 625 1), The Swedish Board o f Technological Development, The Swedish Natural Science Foundation, Magn. Bergvall Foundation and King Gustaf the Vth 80-year Foundation.