Biofilm Initiation Research Articles

Effect of Polymer Surface Properties on the Reversibility of Attachment of Pseudomonas aeruginosa in the Early Stages of Biofilm Development

Biofilm fouling is a common problem in industrial water and medical systems. Prevention of biofilm formation is often difficult because of the numerous potential attachment and adhesion mechanisms of bacteria, and therefore removal strategies are often necessary. Three surface properties, surface roughness, hydrophobicity (contact angle), and surface charge (zeta potential) were measured for several polymeric surfaces and related to specific biofilm characteristics. Biofilms of Pseudomonas aeruginosa were allowed to form on these surfaces for a period of 1-3 d, and the fraction of bacterial cells removed from each surface by exposure of biofilms to a standard shear stress was determined. Cells were most readily removed from the smoothest, most hydrophilic, neutral surfaces, with removal becoming more difficult at longer attachment times. This finding correlates directly with the finding that surfaces with these characteristics are most resistant to biofilm initiation. Therefore, it is demonstrated that by optimizing surface properties, it is possible to produce a surface from which bacteria can be more readily removed.

Effects of ultrafiltration membrane surface properties on Pseudomonas aeruginosa biofilm initiation for the purpose of reducing biofouling

Biofilm fouling is one of the major obstacles hindering the use of membranes in water processing systems. There are a series of events that take place during biofilm formation, one of the most interesting and important issues of biofouling is the initial attachment of microorganisms to the surface. Therefore, effects that surface properties have on biofilm fouling are important to attachment and were examined. Hydrophobicity, surface charge and roughness were measured for several polymeric surfaces of interest in water processing membrane systems. These surfaces were then subjected to conditioning layer formation and biofilm fouling, both of which were quantified. The results show that biofilm initiation by a strain of Pseudomonas aeruginosa increases as the surface becomes more rough and more hydrophobic, while fouling is minimal when surface charge is minimized and increases with increasing charge, whether positive or negative.

Surface charge characteristics of sulphate‐reducing bacteria and the initiation of a biofilm on mild steel surfaces

The surface charge on Desulfovibrio desulfuricans particles grown in iron‐rich batch culture was monitored using electrophoretic mobility. Negative mobility was seen to tend towards zero as growth proceeded and this correlates with cell aggregation and the formation of a biofilm on a mild steel surface. Aggregate size can further be correlated with the relative amounts of sulphur and iron found in them. However, interference with this aggregation and surface treatments showed complex processes to be involved. Biofilm initiation was found to extend over a more lengthy period after batch growth had ceased and corrosion continued during this time. Whilst prevention of biofilm formation reduced corrosion, SRB biofilm formation and sulphide incorporation did not inevitably lead to corrosion, but was dependant on other factors such as biofilm consortia and oxygen availability.