Preparation of yeast cells for surface analysis by XPS

Dengis, Pascale B.; Rouxhet, Paul

doi:10.1016/0167-7012(96)00909-8

Cited by 31 publications

(17 citation statements)

References 25 publications

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“…XPS analysis of mercury-laden/unladen cells was performed according to the method described before [17–18]. Yeast cell samples were washed with ddH 2 O, frozen in liquid nitrogen, freeze-drying at 268 K, mounted the obtained powder in a trough and then pressed before being transferred to the analysis chamber of the spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa

et al. 2017

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A pigmented yeast R1 with strong tolerance to Hg2+ was isolated. Phylogenetic identification based on the analysis of 26S rDNA and ITS revealed R1 is a Rhodotorula mucilaginosa species. R1 was able to grow in the presence of 80 mg/L Hg2+, but the lag phase was much prolonged compared to its growth in the absence of Hg2+. The maximum Hg2+ binding capacity of R1 was 69.9 mg/g, and dead cells could bind 15% more Hg2+ than living cells. Presence of organic substances drastically reduced bioavailability of Hg2+ and subsequently decreased Hg2+ removal ratio from aqueous solution, but this adverse effect could be remarkably alleviated by the simultaneous process of cell propagation and Hg2+ biouptake with actively growing R1. Furthermore, among the functional groups involved in Hg2+ binding, carboxyl group contributed the most, followed by amino & hydroxyl group and phosphate group. XPS analysis disclosed the mercury species bound on yeast cells was HgCl2 rather than HgO or Hg0.

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Section: Methodsmentioning

confidence: 99%

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa

et al. 2017

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“…The temperature of the freeze-dryer shelf was maintained at Ϫ50°C for 3 h; then it was increased to Ϫ5°C over 15 h and maintained at Ϫ5°C for 6 to 12 h; finally, it was increased to 23°C over 3 h. The dehydrated cell powder was homogenized with a spatula and pressed with a polyacetal cylinder cleaned with isopropanol. More details of the procedure can be found in a previous paper (10).…”

Section: Methodsmentioning

confidence: 99%

Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Boonaert

Rouxhet

2000

Appl Environ Microbiol

Self Cite

203

145

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The surface chemical composition and physicochemical properties (hydrophobicity and zeta potential) of two lactic acid bacteria, Lactococcus lactis subsp. lactis bv. diacetilactis and Lactobacillus helveticus, have been investigated using cells harvested in exponential or stationary growth phase. The surface composition determined by X-ray photoelectron spectroscopy (XPS) was converted into a molecular composition in terms of proteins, polysaccharides, and hydrocarbonlike compounds. The concentration of the last was always below 15% (wt/wt), which is related to the hydrophilic character revealed by water contact angles of less than 30°. The surfaces of L. lactis cells had a polysaccharide concentration about twice that of proteins. The S-layer of L. helveticus was either interrupted or crossed by polysaccharide-rich compounds; the concentration of the latter was higher in the stationary growth phase than in the exponential growth phase. Further progress was made in the interpretation of XPS data in terms of chemical functions by showing that the oxygen component at 531.2 eV contains a contribution of phosphate in addition to the main contribution of the peptide link. The isoelectric points were around 2 and 3, and the electrophoretic mobilities above pH 5 (ionic strength, 1 mM) were about ؊3.0 ؋ 10 ؊8 and ؊0.6 ؋ 10 ؊8 m 2 s ؊1 V ؊1 for L. lactis and L. helveticus, respectively. The electrokinetic properties of the latter reveal the influence of carboxyl groups, while the difference between the two strains is related to a difference between N/P surface concentration ratios, reflecting the relative exposure of proteins and phosphate groups at the surface.In many instances, the behavior of lactic acid bacteria is dependent on interfacial processes and thus on cell surface physicochemical properties and chemical composition. A better knowledge of these aspects would allow a deeper understanding of the autolysis of lactic acid bacteria (29, 36) and the production of texturing exopolysaccharides (4). It would help in controlling the sedimentation of starters for commercial production (7) and in understanding the roles of specific and nonspecific interactions in phage attachment (7,46,56).In dairy product manufacturing, adhesion of lactic bacteria to a material may be the first step leading to biofilm formation, which can be either deleterious (contamination, taste alteration, and biofouling on heat exchangers) (17, 25) or beneficial (continuous inoculation in yogurt or cheese making) (5). The adhesion behavior of microbial cells has been shown to depend on the balance of electrostatic and van der Waals interactions and on the hydrophobic character of the surfaces involved (38,42,53,54), pointing to the possible influence of the respective zeta potentials and surface hydrophobicities. Moreover, the production of extracellular substances either at the cell surface or in the surrounding medium has been shown to influence adhesion (14, 55).The surface hydrophobicity and composition of lactic acid bacteria have been studie...

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“…[3 -5] The procedure was evaluated and optimized using brewing yeast cells. [6,7] The relevance and interest of XPS data with respect to the real cell surface is supported by relationships with the nature and physiological state of the microorganisms, as well as by correlations with surface electrical properties and hydrophobicity, and microbial cell behavior at interfaces. [4,8] However, rearrangements of the macromolecular network at the surface, resulting from freezing or water removal, cannot be excluded.…”

Section: Introductionmentioning

confidence: 97%

“…[4,8] However, rearrangements of the macromolecular network at the surface, resulting from freezing or water removal, cannot be excluded. [7] Low temperature XPS (LTXPS) was extensively used to reduce degradation. XPS spectra of lyophilized histidine recorded at low temperature showed a degree of protonation in agreement with expectation from solution, but the spectra recorded at room temperature revealed a deprotonation due to the loss of HCl.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the oil–water interface by XPS at low temperature

Genet¹,

Cogels²,

Adriaensen³

et al. 2008

Surface & Interface Analysis

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A protocol was set up to achieve good control and monitoring of the XPS analysis of hydrated specimens, which involves the ability to freeze the sample before its introduction into the spectrometer, to maintain ice under UHV and to control ice sublimation. The methodology was applied successfully to a model system consisting of a drop of water deposited on a film of triolein containing traces of a phospholipid (dipalmitoyl phosphatidylcholine). Phosphorus and nitrogen, characteristic of the phospholipid, were demonstrated to be accumulated at the spot of the initial oil-water interface. The redistribution of the phospholipid after oil melting could be monitored in real time. The method is promising not only to study surface rearrangements on hydrated systems after water removal but also to get analytical information on gas-water interfaces and on interfaces between two liquids differing according to volatility.

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Preparation of yeast cells for surface analysis by XPS

Cited by 31 publications

References 25 publications

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa

Hg tolerance and biouptake of an isolated pigmentation yeast Rhodotorula mucilaginosa

Surface of Lactic Acid Bacteria: Relationships between Chemical Composition and Physicochemical Properties

Analysis of the oil–water interface by XPS at low temperature

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