Biofilms | UPSC

A biofilm is an assemblage of microbial cells that is irreversibly associated (not removed by gentle rinsing) with a surface and enclosed in a matrix of primarily polysaccharide material.
Van Leeuwenhoek, using his simple microscopes, first observed microorganisms on tooth surfaces and can be credited with the discovery of microbial biofilms.
Microorganisms that form biofilms include bacteria, fungi, and protists.
Noncellular materials such as mineral crystals, corrosion particles, clay or silt particles, or blood components, depending on the environment in which the biofilm has developed, may also be found in the biofilm matrix.
Biofilms may form on a wide variety of surfaces, including living tissues, indwelling medical devices (devices in the body like catheters, heart valves), industrial or potable water system piping, or natural aquatic systems.
As they attach to each other and to the surfaces, they are capable to act as barriers to antibiotics.

Biofilm formation begins when free-floating microorganisms such as bacteria come in contact with an appropriate surface and begin to put down roots.
This first step of attachment occurs when the microorganisms produce a gooey substance known as an extracellular polymeric substance (EPS).
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.