What are biofilms? Biofilms are a complex matrix of bacteria, fungi, and algae bound together in a sticky gel of polysaccharide and other organic contaminants attached to a surface. The bacteria produce a slime layer in which they live that anchors them firmly to a surface and which provides a protective environment to grow and reproduce. Biofilms generally form on any wet surface and are consequently found in many types of environments, especially poultry drinking water systems. Biofilms harbor harmful microorganisms such as Campylobacter, Listeria, Salmonella, E. Coli, Pseudomonas, and Staphylococcus. The existence of biofilm reduces the effectiveness of common disinfectants.
As previously stated, poultry watering systems harbor biofilms. Water sources, such as well or surface water that contain high mineral content, iron bacteria, or coliform, may produce biofilms. The use of vitamins or other sugar based products (Gatorade, Kool-Aid, etc.) is a food source for the microorganisms and will promote the formation of biofilms as well. Problems associated with biofilms in the poultry drinking water include a decrease in poultry survival time, lowered egg production, deterioration of equipment, and clogging of nipple drinkers. Utilizing public water systems or a applying a disinfectant throughout the grow-out (Chlorine gas, chlorine dioxide/anthium dioxide, iodine, or ozone) will not make a farm immune to these biofilm.
Traditional disinfectants do not effectively penetrate the biofilm matrix. The disinfectant must have access to the bacteria in order to be effective. Most disinfectants are active against planktonic (unattached) microorganisms but are not effective against microorganisms in biofilm. In order to penetrate and remove biofilms, it is necessary to hydrolyze the biofilm matrix. Hydrolysis breaks up the biological material and exposes the microorganisms within it to the killing action of disinfecting agents. Below are some products commonly utilized in the industry that are not effective against biofilm:
- Quats are surface antimicrobials. They have no chemical reactivity with biofilm polysaccharide and are bound up by negative charge on the biofilm surface. Quats leave much of the biofilm matrix intact and do not remove or destroy endotoxins.
- Chlorine Dioxide is a strong oxidizing agent. Chlorine Dioxide reacts with the surface of the biofilm but provides no hydrolytic breakdown of the biofilm matrix or mechanical removal.
- Peracetic Acid is active on surface regions of biofilm, but is rapidly neutralized by catalase. There is no hydrolysis or mechanical breakdown of biofilm matrix polysaccharides.
- Citric acid, muriatic acid, sodium hydrogen sulfate, and other acidifiers used to lower pH are neither approved biocides (ability to kill microorganisms) nor biodispersants (ability to penetrate and remove biofilms). These products are effective at removing scale as discussed later.
It is recommended that poultry water lines be cleaned and disinfected with a product that has EPA-registered claims to penetrate and remove biofilm, and to kill biofilm bacteria. Such a product has passed EPA-required tests that establish the efficacy of the product in removing and penetrating biofilm from surfaces and water lines. The above-mentioned quaternary ammonium products, chlorine dioxide, and peracetic acid do not have EPA-registered claims to penetrate and remove biofilms. Some products may carry an EPA registration for a being biocide and are labeled as cleaners. Only evaluation of the product’s label will determine which product is EPA approve for biofilm removal or if it simply kills microorganisms.
What is scale and how is it caused? Hard water is usually associated with well water in regions where the rocks contain a large proportion of minerals such as calcium and magnesium, principally as bicarbonates, and sometimes iron and manganese. Over time, water containing these minerals will attach to plumbing and form scale. Harder scale is comprised of iron and manganese and is more difficult to remove. Softer scale is comprised mostly of calcium and magnesium and is easier to remove. The pH of the water will also play an important role in the formation of scale, where water with a higher pH (over 7.0) will form harder scale at a faster rate. Water with a lower pH will tend to have a mineral “sludge” present in the lines.
There are several concerns associated with mineral scale. Economic impacts to the grower include clogged plumbing and regulators, pressure loss, and nipple drinkers sticking or leaking. Over time, this is a substantial cost when one considers the time and money of replacement. Pretreated water (i.e. filtered or softened water), is a cost effective means of reducing/preventing future problems.
Scale has a rough surface that contains pitting, cracks, and crevices which can harbor microorganisms. Disinfectants such as chlorine and iodine simply pass over these cracks and crevices and the microorganisms will continue to flourish. Therefore, additional treatment measures must be used.
To remove the scale, the pH of the water must be reduced by adding an acid to dissolve the mineral scale. However, the biofilm has to be removed first. An acid can not fully penetrate and will not hydrolyze the biofilm and thus can not dissolve the scale. Consequently, a product with EPA-registered claims to penetrate and remove biofilm must be used before scale can be dissolved. Follow the instruction of the acid product manufacturer for proper use and safety guidelines. The influent pH of the water should also be considered. Water with a natural pH of 8.5 requires the use of more acid than water with a natural pH of 7.2.
There is a common misconception that chlorinated water does not require any maintenance and lines do not have to be flushed. This is absolutely false. Public water, treated well or surface water may reduce the severity of contamination in the lines. However, the lines still remain susceptible to biofilm formation. Regardless of the water quality or water source, it is highly encouraged to clean the water lines between flocks. The grower will realize significantly higher productivity and profits over time with a proactive versus a reactive program.
Any farm that has included water in its Biosecurity program and follows the quality assurance measures set in place by the company’s veterinarian will have a distinct advantage over those that do not. Poultry production is more competitive than ever before and clean water will surely make a difference in the profitability for the grower.