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Azeredo, Joana; Meinders, Jan Marten; Feijó, J.; Oliveira, Rosário

doi:10.1023/a:1018439916772

Cited by 8 publications

(1 citation statement)

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“…After 2 h of incubation, the glass slides were withdrawn from the suspensions and rinsed for 30 s in demineralised water to remove loosely adhering cells. The rinsed slides were dried in Petri dishes at 30°C for 24 h. The adhering cells were enumerated by an automatic image analysis system connected to a microscope (Zeiss-Germany), as described elsewhere [17]. For each experiment, eight plates were analysed and 10 images of each plate were taken, giving a total number of 80 images analysed.…”

Section: Adhesion Studiesmentioning

confidence: 99%

Exopolymers in bacterial adhesion: interpretation in terms of DLVO and XDLVO theories

Azeredo

Visser

Oliveira

1999

Colloids and Surfaces B: Biointerfaces

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149

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Exopolymers have an important role in bacterial adhesion and are associated with irreversible adhesion. Moreover, they can coat surfaces enhancing or avoiding bacterial colonisation. To study the role of exopolymers in the adhesion of bacteria to glass, three mutants of Sphingomonas paucimobilis (which are high (TR), medium (CV) and low (F72) exopolymer producers), were used. The adhesion tests were performed in phosphate saline buffers and in solutions of the exopolymer produced by each mutant. The DLVO theory was able to explain the results in phosphate saline buffers, although this theory could not explain the results obtained in the presence of the exopolymer. The XDLVO theory enabled the interpretation of the results in the presence of the exopolymer, where hydrophobic interactions played an important role. However, polymeric interactions that are not taken into account in these two theories are also expected to be determinant in the adhesion process.

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Section: Adhesion Studiesmentioning

confidence: 99%

Exopolymers in bacterial adhesion: interpretation in terms of DLVO and XDLVO theories

Azeredo

Visser

Oliveira

1999

Colloids and Surfaces B: Biointerfaces

Self Cite

149

View full text Add to dashboard Cite

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The effects of a biocide and a surfactant on the detachment of Pseudomonas fluorescens from glass surfaces

Simões

Cleto

Pereira

et al. 2008

International Journal of Food Microbiology

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Application of antimicrobial chemicals is a general procedure in the cleaning and disinfection of food-contacting surfaces. Adhesion to glass surfaces and chemically induced detachment of Pseudomonas fluorescens ATCC 13525(T) were studied in situ, under flow conditions, in a well-controlled parallel plate flow chamber (PPFC). Ortho-phthalaldehyde (OPA) and cetyltrimethyl ammonium bromide (CTAB) were applied separately, at several concentrations, to attached bacteria and their subsequent detachment was monitored. Following treatments the remaining adhered bacteria were characterized in terms of viability and cell size. Simultaneously, the planktonic cell surface was characterized in order to correlate PPFC results with thermodynamic approaches for adhesion evaluation, and surface free energy of chemically treated cells with adhesion strength. About 2.8x10(6) cells/cm(2) adhered to the glass surface after 30 min of bacterial flow, although thermodynamic analyses evidenced unfavourable adhesion. The independent application of OPA and CTAB promoted bacterial detachment to a small extent (16% of total cells). The remaining adhering bacteria were totally non-viable for OPA> or =0.75 mM and CTAB> or =0.25 mM, showing a lack of correlation between bacterial viability and detachment. The cellular size decreased as attachment proceeded and with chemical treatment. Both chemicals altered the cell surface properties, increasing the cell-glass adhesion strength, and promoting the emergence of polar characteristics. The overall results emphasize that OPA and CTAB were markedly ineffective in removing glass-attached P. fluorescens, demonstrating that bacteria can be non-viable but remain strongly attached to the adhesion surface.

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