Biofilm and Its Formation in Water System : Pharmaceutical Guidelines

Biofilm and Its Formation in Water System

Biofilm formation in pipelines of water distribution system during the continuous running of system and methods to remove it.
Biofilm is a well-known problem of water systems in pharmaceuticals. It is produced by the bacteria and other organisms of various species. Bacteria and other microbes are attached to the inner surface of the water pipelines and start colonizing.

Sometimes pathogens can also participate in the formation of biofilms in the water distribution system. E.coli and Salmonella are more likely to be found in biofilms.

Biofilm formation in water system starts with the attachment of free-floating bacteria to the inner surface of water supply pipeline. Polymucosaccharides, secreted by bacteria helps to attach to the surface and cannot be detached with gentle rinsing. If these initially attached cells are not removed, these cells grow on the surface forming colonies and permanently attached to the surface with the help of pili and flagella

Biofilm Formation

These cells are embedded in a self-prepared matrix known as slime layer or EPS (Extracellular Polymeric Substance) which protects them from the external environment. Slime layer is an initial stage of biofilm formation and produced by the byproducts secreted by these attached microorganisms. These slime layers are hydrophobic in nature that helps the microorganisms remain attached to the surface.

After the maturation of biofilm, it starts releasing microorganisms spreading in water which cause continuous contamination in the water system.

Biofilm formation takes a very short period if water remains stagnant in water distribution system.  Dead legs and rough surface also cause the biofilm formation. Therefore, water system should always remain in continuous recirculation having a smooth surface and no dead leg. These biofilms cannot be disinfected easily and re-colonize again in the very short time period after the removal of disinfecting agent. Most of the biofilms are resistant to weak disinfectants as chlorine, ozone etc.

Biofilm-associated microorganisms are also resistant to low concentrations of antibiotics than free-living microbes. E.coli in biofilms requires 500 times more concentrate amphicillin to get 3 log reductions and Staphylococcus aureus requires 10 times more concentration of vancomycin to get 3 log reductions.

The properties of biofilm-associated bacteria may completely differ from the free-living bacteria of same species. The growth of microorganisms remains slow then the free-living probably because of the availability of the nutrients available in the biofilms.

These biofilms also damage the pipes because of the presence of sulfate-reducing bacteria those produce hydrogen sulfite as a byproduct. This hydrogen sulfite reacts with the iron of pipes causing leakage and breaks down.

Biofilm Removal from Water System

Removal of biofilm from water system is not an easy task. It is always much better to prevent the system from the biofilm formation than its removal. But when occurred it is first treated with strong acid i.e. nitric acid followed by strong base i.e. sodium hydroxide. 

By these, both inorganic and organic compounds associated with the biofilm are removed very effectively resulting its separation from the surface. Now the whole system is disinfected with the strong disinfectants as hydrogen peroxide. Use of UV light in the water system is an effective way to prevent the biofilm formation.

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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