FAQ on Biofilm
- What are biofilms?
Biofilms are the thin layers of microorganisms held together by secreted substances that are attached to a surface or present as congregates suspended in liquid. These microorganisms are embedded in a self-producing matrix of extracellular polymeric substances (EPS) made of polysaccharides, proteins, nucleic acids, lipids and bacteriophage. A biofilm assemblage can be formed by a single species of bacteria, but biofilms in nature are mostly communities made up of multiple species of bacteria, fungi, algae and other microorganisms.
- Where can you find biofilms?
Biofilms are the default mode of life for microorganisms and can be found everywhere - as long as there is moisture and nutrients. The slippery coating on rocks in a river, the clumps that clog up pipes and the layer of plaque on our teeth are common examples of biofilms. They can form on all kinds of surfaces: natural materials, plant and animal tissue, as well as manufactured materials like metals and plastics. Although they are predominantly found on surfaces, biofilms can also form when microbes cluster together in suspension, attaching to each other via the EPS. Here they are known as flocs or granules (terminology commonly used in used water treatment)
- What are the advantages for bacteria to be in biofilms?
The biofilm lifestyle allows microbes to live in close proximity to each other, enhancing fitness by sharing genetic material through horizontal gene transfer, undertaking metabolic cooperation by dividing tasks and cycling nutrients, and taking advantage of nutrient and electrical gradients. Indeed, it is not uncommon for microbes within a biofilm to display altruism, sacrificing themselves for the benefit of the community.
The matrix itself also imparts significant benefits to biofilm microbes, such as resistance to external stressors. Bacteria that live in biofilms have better survivability because the EPS protects the cells and serves as a medium for interaction and coordination. Biocides and antimicrobial agents cannot easily penetrate the coating to reach the innermost cells. As a result, the strongest disinfectants at environmentally safe concentrations will often only kill those bacteria on the outside of a biofilm. In fact, bacteria inside biofilms can tolerate antibiotic levels up to 1,000 times higher than the dose required to kill free-floating bacteria.
- Why are biofilms important?
Biofilms are nature’s recyclers. They play an integral role in the biogeochemical cycles in every ecosystem on the planet. Without microbial biofilms nutrient cycling would not be possible and the constant regeneration of natural – and engineered – systems would cease.
In man-made environments, biofilms have a big impact on industrial, agricultural and food distribution systems, and human health. They can be found in urban waterways, wastewater processing plants, oil pipelines, on the hulls of ships, food processing plants and on all surfaces of the human body.
Globally, the adverse effects of biofilms cost billions of dollars every year due to energy losses, equipment damage, product contamination and medical infections and treatments. The NIH estimates that about 80% of all human infections are biofilm-related, with the majority of all chronic infections attributed to biofilms. Thus, there is an increasing interest to study biofilms in detail, with research contributions from diverse fields such as microbiology, biochemistry, engineering and mathematics. This is especially pertinent given the continual loss of efficacy of antibiotics worldwide. Understanding biofilm biology holds the key to developing dispersal technologies that restore the efficacy of antimicrobials.
Estimations of the economic benefits of biofilms have not been ventured. However, when considering the integral roles they play in key systems such as mutualistic interactions with host organisms, including humans (together known as holobionts), bioremediation processes, used water treatment, to name a few, the benefits are staggering.
- Are biofilms good or bad?
Microbial biofilms are an ancient mode of life and have contributed to the world as it exists today. Without biofilms we would not be able to function or maintain the environments needed to persist. From a human perspective, however, they can be viewed as having both positive and negative impacts on our world.
Throughout the millennia, microbial biofilms have evolved enormous metabolic capabilities to cope with and take advantage of conditions in every environment imaginable. These metabolisms can be harnessed to perform any number of beneficial tasks, especially in urban settings where a natural balance is often lost. In association with higher organisms, microbial biofilms can maintain the health of their host by deterring pathogens and aiding nutrient acquisition and synthesis. Biofilms can also be put to work in industrial and agricultural settings, treating wastewater for reuse, acting as biobarriers to protect the soil from contamination and bioremediating contaminated land and waterways.
Of course, biofilms also have a negative side. They are the main agents in chronic infections and disease, they cause corrosion in industrial, commercial and maritime settings, block filters in water treatment and desalination plants, contaminate food processing equipment and cause drag in aquatic vessels and structures through biofouling.
It is this dual nature of biofilms that SCELSE is targeting; insights from biofilm research will allow the negative aspects of biofilms to be managed and the positive aspects to be harnessed for a wide range of beneficial applications.