Biofilms in Microbiology

Biofilms are a collective of one or more types of microorganisms that can grow on many different surfaces. Microorganisms that form biofilms include bacteria, fungi and protists. 

One common example of a biofilm dental plaque, a slimy build-up of bacteria that forms on the surfaces of teeth. Pond scum is another example. Biofilms have been found growing on minerals and metals. They have been found underwater, underground and above the ground. They can grow on plant tissues and animal tissues, and on implanted medical devices such as catheters and pacemakers. 

Biofilm formation begins when free-floating microorganisms such as bacteria come in contact with an appropriate surface and begin to put down roots, so to speak. This first step of attachment occurs when the microorganisms produce a gooey substance known as an extracellular polymeric substance (EPS), according to the Center for Biofilm Engineering at Montana State University. An EPS is a network of sugars, proteins and nucleic acids (such as DNA). It enables the microorganisms in a biofilm to stick together.

Attachment is followed by a period of growth. Further layers of microorganisms and EPS build upon the first layers. Ultimately, they create a bulbous and complex 3D structure, according to the Center for Biofilm Engineering. Water channels crisscross biofilms and allow for the exchange of nutrients and waste products, according to the article in Microbe. For microorganisms, living as a part of a biofilm comes with certain advantages. "Communities of microbes are usually more resilient to stress," Gerlach told Live Science. Potential stressors include the lack of water, high or low pH, or the presence of substances toxic to microorganisms such as antibiotics, antimicrobials or heavy metals. There are many possible explanations for the hardiness of biofilms. Finally, the cells within a biofilm can leave the fold and establish themselves on a new surface. Either a clump of cells breaks away or individual cells burst out of the biofilm and seek out a new home. This latter process is known as "seeding dispersal," according to the Center for Biofilm Engineering.

Media Contact:

Eliza Miller
Managing Editor
Microbiology: Current Research
Email: aamcr@alliedacademies.org