“Brush your teeth so that you won’t get plaque.” How many times have you heard that from your dentist?
Dental plaque is a common example of a biofilm, a community of microorganisms that sticks together thanks to a dense, glue-like extracellular (outside the cell) substance.
These communities can get pretty big. For example, back in 1684, the well-known Dutch scientist Antonie van Leeuwenhoek saw biofilms when he observed dental plaque under a microscope. In a report, he wrote: "The number of these animalcules in the scurf of a man's teeth are so many that I believe they exceed the number of men in a kingdom.” In other words, he saw a lot of microorganisms living in a biofilm!
Biofilms might sound gross, and they can definitely be dangerous in some situations. And other times, they can actually be quite helpful.
How are biofilms formed?
It all starts with free-floating microorganisms, often a species of bacteria. They stick to a surface using their own glue. They then provide places for other cells to stick to, making it easier for more and more cells to join. Gradually, they begin to build the matrix that holds the biofilm together. The biofilm grows by recruiting more cells, and also by cell division.
Did you know? Biofilms are usually named after what's living inside. For example, there can be fungal biofilms, fungal-bacterial biofilms, and many more.
Biofilms are usually found on solid surfaces. These can include abiotic surfaces (like the inside of a pipe) and biological surfaces (like teeth, or even animal gut surfaces).
What is special about biofilms?
Living in a biofilm comes with advantages. For example, the biofilm’s dense matrix can protect a microorganism from substances that might hurt it, like detergents (cleaning agents) and antimicrobial chemicals.
Also, some biofilms can communicate, sending each other chemical and physical signals to share information about their environment. This can be true even when they’re different species!
Did you know? Bacterial biofilms are the biofilms that scientists most commonly study.
Common biofilms and their effects
Bacterial biofilms can cause a lot of problems for people. We’ve already talked about plaque, but biofilms can lead to other dental problems as well. Plaque bacteria stick to your teeth and can digest food particles. This creates acidic substances that can decay your teeth.
Also, biofilms can form on implanted medical devices such as pacemakers, wires or tubes in a patient’s body. These biofilms can eventually lead to an infection. What’s worse, because their extracellular matrix is so protective, biofilms tend to be resistant to some antibiotics. This makes it especially difficult for doctors to treat infections like these!
Finally, biofilms can start problems outside of the body, too. Remember, some biofilms are resistant to detergents. That can make it really hard to sanitize floors, counters and other surfaces they appear on!
Advantages of biofilms
But biofilms have certain advantages as well, especially in industrial applications. For example, biofilms are helpful in sewage treatment. They grow on filters, and when waste water passes through, they extract and digest harmful material from it.
Some scientists are struggling to find solutions to the complications biofilms can cause. Meanwhile, other scientists are keenly investigating new ways to use biofilms.