Biofilms are an aggregate of microorganisms (minute organisms invisible to naked eye), wherein the cells stick on to each other to form a matrix like structure. These microorganisms that are embedded into this matrix grow and develop into a microbial film. Biofilms development may take 24 hours and can grow to millimeters in few days. This matrix is made up of organic polymers or polysaccharide and is known as glycocalyx. This glycocalyx layer protects the microorganisms from the sanitizers. The first scientist to have discovered biofilms was Van Leeuwenhoek, who using his microscope first observed microorganisms on tooth surface.
Various experts in the field of Microbiology have documented that, majority of the human infections result from biofilms. Thus, the biofilms needs to be studied in great detail as they have a vital role in causation of human infection. Many investigators have reported formation of biofilms in aqua marine systems, in food processing equipments, food processing environments, etc. Formation of biofilm not only results in human infections, but also results into equipment damage, product contamination, energy losses and medical infections.
Biofilms are of prime importance in the area of food hygiene. This is so because, human pathogens have the ability to attach and grow both on food as well as food contact surfaces under favorable conditions which enhances their ability to survive harsh environment to resist antimicrobial treatments, and to spread and persist in the food processing environment. Biofilms have the ability to grow in extreme conditions, for example, in extremely hot, briny waters of hot springs ranging from very acidic to very alkaline, to frozen glaciers. It has also been reported that the bacteria present in the biofilms are more resistant to heat as well as sanitizers as compared to their free living (planktonic) counterparts. Biofilm forming bacteria include Listeria, Salmonella, Campylobacter, E coli, Pseudomonas, lactic acid producing bacteria and thermo tolerant species. They may occur as mixed cultures, but often single species will dominate.
Formation of a biofilm begins with the attachment of free-floating microorganisms to a surface. These first colonies adhere to the surface initially through weak, reversible van de Waals forces. If the colonies are not immediately separated from the surface, they can anchor themselves more permanently using cell adhesion structures such as pili.
As explained above once a biofilm is formed is difficult to remove and therefore it becomes necessary to study various methods necessary to prevent the formation of biofilm. Also more research needs to be carried out in order to design new and more reliable methods for cleaning and sanitizing the surfaces that would ensure the complete removal of the microorganisms embedded in the matrix.
