Biofilm is a colonial structure formed by microorganisms in order to survive and adapt in adverse environmental conditions. In nature, biofilms alternate in two modes of growth: planktonic (free-floating state) and sessile (when microorganism adhere to the surface). Diverse species of microorganisms are involved in biofilm formation, such as bacteria (e.g., Pseudomonas, Staphylococcus, E. coli, etc.), fungi (e.g., Candida, Aspergillus), and protozoa (e.g., amoebae, heliozoa).
Biofilms produce extracellular polymeric substance (EPS) known as "slime," which comprise polysaccharides, proteins, phospholipids, teichoic acids, and nucleic acids. In most biofilms, the matrix comprises more than 90 percent of the dry mass, while the microorganism accounts for less than 10 percent. The EPS provides protection to the microbial cells against environmental stressors by forming a mushroom-shaped protective barrier surrounding the microbial colonies, thereby favoring the growth of biofilm formation.