The impact of microbial biofilms on water quality

Environmental Science

The Impact of Microbial Biofilms on Water Quality

Microbial biofilms are complex communities of microorganisms that adhere to surfaces and form a protective matrix of extracellular polymeric substances (EPS) composed of proteins, polysaccharides, and nucleic acids. They can be found at the interface of different environments, including water, soil, plants, and animals. In aquatic systems, biofilms play a vital role in maintaining water quality, but they can also pose a threat to human health and the environment.

What are microbial biofilms?

Microbial biofilms are communities of microorganisms that attach to surfaces and grow in three-dimensions through cell division and extracellular matrix production. The matrix provided by EPS serves as a protective layer that offers resistance to environmental stressors and predation. The matrix also facilitates the exchange of nutrients and metabolites, allowing for cooperative interactions between the different microbial species present in the biofilm. Biofilms are found in various aquatic environments, including freshwater, marine, and estuarine systems. They can be found on biotic and abiotic surfaces, such as rocks, pebbles, sand grains, and plant surfaces. In natural environments, biofilms can be found on submerged surfaces such as streambeds or river rocks. In artificial systems, biofilms form on surfaces such as water pipes, water treatment systems, and filters.

Functions of microbial biofilms in water quality

Biofilms play an important role in maintaining water quality. They provide ecosystem services, such as nutrient cycling, primary production, and degradation of organic matter. In aquatic systems, biofilms play an essential role in the production and maintenance of food webs. Biofilms serve as a primary food source for many aquatic organisms, including invertebrates, fish, and other vertebrates. Biofilms also contribute to the assimilation and removal of nutrients from the aquatic systems. The EPS matrix facilitates nutrient exchange between the microbial cells, and the uptake of nutrients by the biofilms can help prevent eutrophication and algal blooms. Biofilms can also serve as carbon sinks, assisting with the uptake of carbon dioxide from the atmosphere.

Impact of microbial biofilms on water quality

While biofilms play an essential role in maintaining water quality, they can also have negative impacts. Biofilms can create a biofouling problem in water distribution systems, filters, and membranes, which can compromise water quality. Biofilms can also act as a reservoir for pathogenic microorganisms, including bacteria, viruses, and protozoa. Pathogens can live within the biofilm matrix, making them more resistant to disinfection and difficult to remove from water systems. Biofilm formation can also lead to the release of harmful chemicals, such as heavy metals, and organic pollutants from industrial sources. The EPS matrix can adsorb these chemicals and potentially release them into the environment, which can negatively impact aquatic ecosystems. In addition, biofilms can cause corrosion of metal pipes and surfaces, leading to the release of metals into the water.

Control of microbial biofilms

Controlling microbial biofilms is important to maintain water quality and ensure human health. Various methods can be used to control biofilm formation, including physical, chemical, and biological methods. Physical control focuses on removing the biofilm by mechanical means, such as scraping or brushing. Chemical control involves the use of oxidizing agents, disinfectants, and antimicrobial agents. Biological control includes the use of bacteriophages, probiotics, and competition between different microbial species. Developing effective methods to control biofilms requires a precise understanding of the microbial ecology and environmental factors that influence biofilm formation and growth. Interventions that prevent initial biofilm attachment are more effective than treatments that aim to remove mature biofilms.


In conclusion, microbial biofilms have a profound impact on water quality. Biofilms play an essential role in maintaining ecosystem health by providing ecosystem services, such as nutrient cycling and primary production. However, biofilms can also create problems by acting as a reservoir for pathogenic microorganisms, causing biofouling, and releasing harmful chemicals into the water. Effectively controlling microbial biofilms requires a precise understanding of microbial ecology, environmental factors, and the development of optimal interventions that prevent initial biofilm attachment.