McEldowney, Sharron (1984) Attachment of freshwater bacteria to solid surfaces. PhD thesis, University of Warwick.

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Abstract

The initial stages of the permanent attachment of selected
freshwater bacteria, particularly Pseudomonas fluorescens, Enterobacter
cloacae, a Chromobacterium sp and a Flexibacter sp, to a hydrophobic and
a relatively hydrophilic polystyrene surface was investigated.
Changes in the nutrient conditions and growth rates of the bacteria
caused differences in cell surface characteristics, measured by
hydrophobic and electrostatic interaction chromatography and saline
contact angle measurements on lawns of cells, and changed attachment
levels to the two substrata in both buffer and nutrient media. The
effects were different for each species, varying independently with
surface, and were, largely, related to changes in predicted physicochemical
interactions. However, the Flexibacter sp, a gliding
bacterium, showed an increase. in attachment with increased growth rate,
i. e. metabolic activity, possibly indicating an active attachment
process.
Peaks in the attachment of E. cloacae, P. fluorescens and the
Chromobacterium sp to both substrata occurred between pH 6 and 7.5 and
20°C and 25°C, while the Flexibacter sp decreased attachment with
increasing pH and temperature. These changes in attachment for each
species were related to physico-chemical rather than physiological
effects.
Varying the electrolyte concentration and valency of the attachment
solution showed that permanent attachment was independent of diffuse
electrical double layer thickness. Similarly, attachment levels could
not be predicted thermodynamically using liquid, solid and cell surface
tensions, indicating the involvement of electrostatic interactions in
the attachment of these species. Estimates of the hydrophobicity of the
cell surfaces, by hydrophobic interaction chromatography, showed that
hydrophobic interactions did not dominate in bacterial attachment.
Thus, attachment of these four species was a multifactorial interaction
involving a range of physico-chemical interactions.
The attachment of individual species was also found to be affected
by the presence of other bacterial species. Thus in natural aquatic
systems a variety of biological, environmental and physico-chemical
parameters will affect levels of bacterial attachment and hence biofilm
composition and development.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Attachment mechanisms (Biology), Bacteria, Water -- Microbiology
Official Date:	July 1984
Dates:	Date Event July 1984 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Fletcher, Madilyn ; Baker, John R. (John Robin)
Sponsors:	Science and Engineering Research Council (Great Britain) (SERC)
Extent:	[22], 298 leaves
Language:	eng

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