Understanding Biofilms: What, When, and Where

Overview of a Biofilm

A biofilm is a colony of microorganisms held together by extracellular polymeric substance (EPS) and is ubiquitous on any non-sterile wetted surface. They can contain (in addition to the microorganisms themselves) microbial secretions, corrosion products, and entrapped clay and soil materials. Biofilms are present in a broad range of industrial, environmental, human health, and agricultural systems including drinking water, industrial process systems, medical and dental infections, food production and spoilage, and energy production among others. Some beneficial biofilms are cultivated (wastewater treatment, mining, agricultural applications, environmental remediation, and biomass generation), while often biofilms are detrimental to human activities. For example, biofilm in drinking water distribution systems can act as a reservoir for pathogenic organisms for periodic disease outbreaks and deterioration of infrastructure. Industrial systems suffer a loss of efficiency in heat exchangers and cooling towers, as well as fouling and plugging of process lines, leading to increased energy costs. Public health biofilm issues include the identification of biofilm as a persistent source of contamination associated with medical implants, chronic infections, and dental caries leading to serious long-term health impacts for patients and significantly increased medical treatment costs. The consistent theme among biofilms is their ability to thrive under limited nutrients and high-stress conditions, making them difficult to kill and eliminate from process surfaces. These biofilm processes, both beneficial and detrimental, require research devices to reproducibly study and grow biofilms to optimize biofilm active compounds and surface treatments, and to help understand basic biofilm processes.

History of Biofilms

The first observations of biofilms were made in 1698 by the Dutch scientist Antonie van Leeuwenhoek, who described seeing groups of microbial cells through his microscope. Known as the “Father of Microbiology”, Antonie observed what we now know to be a dental biofilm in plaque scrapings from his own teeth. Biofilm research really began later in the 1940s when researchers observed small colonies of bacteria growing together on porous surfaces in water. Bill Costerton gave these colonies of bacteria a name in 1978: biofilm. Early observations were made using a variety of techniques including culturing, microscopy, and flow cytometry. It was not until the early 1990s that researchers began to study more closely the mechanisms that allow the formation and function of these communities and how they contribute to biological processes in their environment.

Extracellular Polymeric Substances

Extracellular polymeric substances (EPS) are a complex mixture of macromolecules, primarily polysaccharides, that are produced and secreted by cells within a biofilm, and can often be up to 90% of all organic carbon found within the biofilm. EPS can serve critical functions for the growth and survival of biofilms. Some of the molecules it contains can protect against environmental stress, while others may facilitate the formation of new colonies by promoting communication and cooperation among the cells (quorum sensing). EPS also plays an important role in the adhesion and colonization of surfaces by providing a surface-attachment matrix for the biofilm. Additionally, EPS can act as a source of energy for cells within the biofilm, which can help support its long-term survival.

Biofilms in Medicine

Biofilms can form on medical devices, surfaces, and in patient rooms, causing a variety of health problems for patients. These problems can range from minor infections to life-threatening conditions. Some of the most common causes of biofilm-related health issues include:

Chronic wounds – Biofilms can cause chronic wounds, which are often difficult to treat and can lead to further illness and death for patients. Symptoms of chronic wounds include pain, infection, and impaired mobility.

Urinary tract infections (UTIs) – UTIs are a common health problem caused by bacteria that have entered the urinary system through the urethra or vagina. UTIs are typically treated with antibiotics, but they can be difficult to cure because they often occur in people with weakened immune systems or who are older or have other underlying medical conditions.

Biofilms may also be a factor in spreading other diseases, such as HIV and antibiotic-resistant bacteria. The US Centers for Disease Control and Prevention has estimated that 1.7 million healthcare-associated infections occur each year (including 98,000 deaths) in hospitals and doctor’s offices, which often take the form or are caused by a biofilm. In many cases, these infections go undiagnosed or unreported due to the poor visibility of microbial communities in biofilms.

To help reduce biofilm attachment and growth, unique surfaces and finishes such as metal alloys or antimicrobial coatings are being developed which can be used on medical equipment and related surfaces. Additionally, surface sanitation and sterilization techniques such as ultraviolet light or chemical agents can help kill and remove biofilm-forming bacteria from the surrounding environment. The use of biofilm reactors and microscopy devices have been instrumental in aiding in the development of these methods and will continue to be a primary source of reliable and repeatable biofilm growth for research applications in the medical field.

Take a look at the following video. This short documentary produced by the Center for Biofilm Engineering (CBE) here in Bozeman, Montana discusses biofilms, some important biofilm topics of research, and other information about the CBE. The CBE is the global leader in biofilm research, and we are lucky to be able to work with them on the development of many of our products for biofilm investigations.

For more information on biofilms: Center for Biofilm Engineering at Montana State University