By Dr Ayushi Verma PhD, product development manager of Duke Thomson India
Biofilm is a “metabolically active matrix of cells and extracellular compounds usually polysaccharides”. Biofilms start with a bacterial adhesion, referred to as a conditioning layer, of inorganic or organic matter forming on an else visually clean food contact surface.
The colonisation of live, dead, or damaged cells begins by attaching themselves to the conditioning layer. Any combination of pathogenic and spoilage bacteria that form on and coat the conditioning layer which is resistant and thin in nature. The biofilm begins to take shape as layers of bacteria attach to the surface and each other, trapping nutrients and debris. They start to produce extracellular polysaccharides (EPS) and change in cell morphology. The EPS material forms a bridge between the bacteria and conditioning layer, with a combination of electrostatic and covalent bonds. The EPS aids in protection of the bacterial layer against sanitisers and cleaners, adhering to the cells in the film.
Bacterial appendages (eg flagella, pili, and fimbriae) may also help in the attachment of other materials or cells to form the colony. For example, L monocytogenes binds to surfaces with attachment fibrils. During attachment, colony-forming cells work together in a coordinated and cooperative fashion, including channelling nutrients to the film and removing waste products. Eventually, mature film reaches an equilibrium that delivers nutrients, food and oxygen, while carrying away sloughed cells and fermentation products.
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