You probably have seen it, a slimy layer of microorganisms adhered to your pipework. This layer is called biofilm. Understanding biofilm and mitigating its harmful effects is critical for a wide range of purposes, ranging from corrosion prevention to treating infectious diseases. This week we answered six stressing questions concerning biofilm.
1. What is biofilm?
Biofilm is a slimy layer of microorganisms that grow on many different surfaces (Vidyasagar, 2016). Nearly every type of microorganism can form biofilm, such as fungi, bacteria, and protists (Corrosionpedia.com, n.d.). In the industry, biofilms can be found on surfaces of aqueous environments, such as pipeline walls.
In scientific terms, biofilm is defined as:
“(…) a community of microorganisms attached to an inert or living surface by a self-produced polymeric matrix or an assemblage of microbial cells associated with a surface and enclosed in a matrix of primarily polysaccharide material.” (Kannan et al., 2017)
2. What are the stages of biofilm formation?
Source: Vasudevan, 2014, J Microbiol Exp 1(3): 00014. DOI:10.15406/jmen.2014.01.00014.
Biofilm formation consists out of 5 steps. Formation begins when free-floating microorganisms come in contact with a surface and attach to it by putting down ‘roots’, so to speak. The attachment occurs when microorganisms produce a slimy substance known as extracellular polymeric substance (EPS) (Vidyasagar, 2016). EPS is a network of proteins, sugars, and nucleic acids (Vidyasagar, 2016). It enables the microorganisms to stay together. After attachment, a period of growth follows. By which layer after layer is formed upon each other. Ultimately, a complex and bulbous structure is made named biofilm. Some of the microorganisms will detach and start the biofilm formation cycle again at a different spot.
3. What is the purpose of biofilm?
For microorganisms, living as a biofilm has certain advantages. Communities of microorganisms are more resilient to stressors (Vidyasagar, 2016). Potential stressors could be a lack of water, presence of toxic substances, and high or low ph. Forming a biofilm is their way to survive under these conditions. For example, EPS acts as a protective barrier against bleach and helps against dehydration.
4. Are biofilms harmful?
Biofilms can be both harmful or beneficial. It depends on the type of biofilm, the type of surface and the effect it has. The biofilms on the inside of our intestines are good for us as they protect the organwall. However, in the industry, biofilm is hazardous for water distribution systems. The layer of biofilm is the breeding ground for dangerous bacteria such as Legionella or E-Coli. Since, biofilm works as a protective layer, it is difficult to eliminate these bacteria with regular prevention techniques. Only a technique that completely dissolves biofilm can guarantee a 100% Legionella safe result. Additionally, biofilm can be dangerous for your pipework as it accelerates the corrosion process.
5. How do biofilms influence corrosion?
Biofilms can accelerate the corrosion process in metal pipelines. They influence this process by:
- generating corrosive substances;
- consuming oxygen (cathodic reactant);
- increasing mass transportation of the corrosion reactants and products, thereby changing the kinetics of the process;
- and, generating substances that can become auxiliary cathodic reactants. (Corrosionpedia.com, n.d.)
In gas and oil industries, biofilms interact with hydrogen present on surfaces of pipelines. They produce, by means of metabolism, a hydrogen sulfide byproduct (Corrosionpedia.com, n.d.). This process can destroy steel and even iron heavy-walled pipes! Resulting in catastrophic leaks and pipeline failure.
6. How can we dissolve biofilm?
Biofilms can be controlled and dissolved by biocides, limiting nutrients, and by biodispersants. Biocides are effective in overall biofilm control, when applied properly (Corrosionpedia.com, n.d.).
The biocidal Legionella prevention technique copper silver ionization completely dissolves biofilm. By the use of electrodes, low concentrations of copper and silver ions are transported through the water. Due to the constant presence of copper and silver ions, the ions will attach and submerge into the biofilm. The strong cooperation between copper and silver will lead to completely disarming the bacteria, both its function and growth.
Ensuring a completely safe drinking water installation!
Good for your pipework // Good for your water // Good for your health
Corrosionpedia.com (n.d.). Biofilm. Retrieved from: https://www.corrosionpedia.com/definition/1649/biofilm
Vidyasagar, A. (2016). What are Biofilms? Retrieved from: https://www.livescience.com/57295-biofilms.html
Rose, J.B., PhD. (2011). Biofilms: the Good and the Bad. Retrieved from: https://waterandhealth.org/safe-drinking-water/drinking-water/biofilms-good-bad-2/
Kannan, M., Rajarathinam, K., Venkatesan, S., Dheeba, B., & Maniraj, A. (2017). Silver Iodide Nanoparticles as an Antibiofilm Agent—A Case Study on Gram-Negative Biofilm-Forming Bacteria. In Nanostructures for Antimicrobial Therapy(pp. 435-456). Elsevier.