Characterisation of bacterial adhesion and removal in a flow chamber by micromanipulation measurements.

Flow device analyses and micromanipulation were used to assess the adhesive and cohesive integrity of the immobilised bacterial populations (biomass) of Pseudomonas fluorescens, which were harvested at different growth times and applied to a substrate made of stainless steel subsequently accommodated in a specially designed flow chamber. After the biomass was exposed to a fluidic environment for a period of time, the biomass samples were removed from the flow chamber and the apparent adhesion and cohesion of the remaining biomass was measured using a micromanipulation technique. The surface area of the substrate covered by the biomass exposed to the fluid flow was monitored by a digital camera and then quantified by image analysis.

Patenting computer-designed peptides.

The problem of designing new peptides that possess specific properties, such as bactericidal activity, is of wide interest. Recently, attention has focused on the use of Computer-Aided Molecular Design techniques in parallel with more traditional 'synthesise and test' methods. These techniques may typically use Genetic Algorithms to optimise molecules based on Neural Network models that predict activity.

Changes in the biocide susceptibility of Staphylococcus epidermidis and Escherichia coli cells associated with rapid attachment to plastic surfaces.

Differences in opacity between wells of a microtitre plate containing different volumes of inoculated growth medium reflected planktonic growth without any contribution from cells attached at the well surface. Simple algebra and a knowledge of the dependence of optical density upon sample path length (volume) for suspensions of differing cell density enables the generation of growth curves for attached populations (biofilms). In this manner, minimum inhibitory concentrations (MICs) were determined at various stages of growth (0-20 h), both for cells growing attached to the bases of the plate wells and, simultaneously, for cells growing in suspension above them.

A Novel Strategy for Control of Microbial Biofilms through Generation of Biocide at the Biofilm-Surface Interface.

Biofilms of a mucoid clinical isolate of Pseudomonas aeruginosa (24 h; ca. 10(sup6) CFU/cm(sup2)) were established by immersion of polymer discs in nutrient broth cultures at 37(deg)C. Biofilms exposed for 30 min to various concentrations (0 to 3 mg/ml) of hydrogen peroxide or potassium monopersulfate were rinsed and shaken vigorously in sterile saline to detach loosely associated cells, and the residual viable attached population was quantified by a blot succession method on agar plates.