A bacterial population structure study of water cooling systems in South Africa

Bacteria forming biofilms occur in all open water cooling systems where they accelerate metallic corrosion, reduce flow rate and decrease heat energy transfer rate. A population structure study of seven systems was conducted. The isolate most frequently encountered was Pseudomonas fluorescens (35,5%), the species commonly used in research regarding biofilm formation. This was followed by Chromobacter violaceum, P. pickettii, P. stutzeri and P. putida, each amounting to 6,6%. The dominant organisms occurred in two groups of over 85% relatedness between their biochemical reaction patterns. Overall four distinguishable groups occurred on the 90% similarity level