"More properly known as biofilm, slime cities thrive wherever there is water - in the kitchen, on contact lenses, in the gut linings of animals. When the urban sprawl is extensive, biofilms can be seen with the naked eye, coating the inside of water pipes or dangling slippery and green from plumbing." (Coghlan 1996)
Simply put, biofilms are a collection of microorganisms surrounded by the slime they secrete, attached to either an inert or living surface. You are already familiar with some biofilms: the plaque on your teeth, the slippery slime on river stones, and the gel-like film on the inside of a vase which held flowers for a week. Biofilm exists wherever surfaces contact water.
More than 99 percent of all bacteria live in biofilm communities. Some are beneficial. Sewage treatment plants, for instance, rely on biofilms to remove contaminants from water. But biofilms can also cause problems by corroding pipes, clogging water filters, causing rejection of medical implants, and harboring bacteria that contaminate drinking water.
For additional information read "The Slimy Truth About Biofilm", an interview with Anne Camper from the Center for Biofilm Engineering.
Why learn about biofilms?
"Microbiologists have traditionally focused on free-floating bacteria growing in laboratory cultures; yet they have recently come to realize that in the natural world most bacteria aggregate as biofilms, a form in which they behave very differently. As a result, biofilms are now one of the hottest topics in microbiology." (Potera 1996)
As in any water system, 99 percent of the bacteria in an automated watering system is likely to be in biofilms attached to internal surfaces. Biofilms are the source of much of the free-floating bacteria in drinking water, some of which can cause infection and disease in laboratory animals. One common biofilm bacteria, Pseudomonas aeruginosa, is a secondary pathogen which can infect animals with suppressed immune systems. Besides being a reservoir of bacteria which can affect animal health, biofilms can also cause corrosion in stainless steel piping systems. In order to design and operate automated watering systems that deliver the bacterial quality required by our customers, we should understand how biofilms develop, some of the problems they can cause, and how they can be controlled.
Understanding bacteria in biofilms is one step in preparing for the future. We are currently meeting the most demanding microbiological water quality requirements of many of our customers by supplying chlorinated reverse osmosis water and by maintaining water quality through flushing and sanitization. (Refer to Microbiological Survey of Automated Watering Systems, D209, Dreeszen 1996.) But, what if chlorine use in animal drinking water is prohibited? Or, what if water quality requirements become even more stringent with the use of new specialized animals?
Of course, you might just want to learn about biofilms to marvel at the ability of bacteria to adapt to their environment and to evade our attempts to eliminate them.
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