Biofilms

Dental Caries Significance

A biofilm is a population or community of bacteria living in an organized structure at the interface between a solid enamel surface and a liquid, saliva. Biofilms are less susceptible to antimicrobial agents to that of free floating planktonic bacteria found in saliva, making them more resilient and difficult to manage.

Oral Biofilm Formation - See it in real time!

In vitro simulation of biofilm forming on enamel surface as human saliva is pulsed over an initially clean surface. Research by Professor Wenyuan Shi, UCLA. The video shows the formation of a biofilm using time-lapsed photography over an 8 hour period.

Initially you will see the colonizers which tend to be streptococcal species of bacteria, these have the ability to produce extracellular polysaccharides which means they can produce a sticky compound that allows them to adhere to the enamel surface.

Biofilm formation at 1600hrs	Biofilm formation at 1900hrs
Biofilm formation at 2200hrs	Biofilm formation at 2400hrs

The following SEM images show the formation of a biofilm over an 8 hour period.

Biofilms are up to 1,000 times more resilent than free floating bacteria.

We know that when bacteria species attach to a biofilm they may undergo as many as 84 genetic mutations and that biofilm bacteria are up to 1,000 times harder to affect in comparison to planktonic free-floating bacteria. This is an important fact to keep in mind when we look at effective ways of treating biofilm diseases.

As the formation continues you will begin to see other species of bacteria colonize. Bacteria within a biofilm live synergistically, one species will metabolize an available nutrient, create a waste product from it and another species will use that waste product as its nutrient. This is a sophisticated and harmonious arrangement with cell to cell communication. You should be able to see the formation of the nutrient and waste channels.

1. Planktonic bacteria attach to a hard surface. 2. Biofilm growth. 3. Detachment following cell to cell communication.	Biofilm matrix builds with increased bacterial activity. Selection pressure influences the bacterial balance.

Images: Courtesy of the Centre of Biofilm Engineering, Montana State University