1. Biofilm: microbial reservoir

Bacteria have the ability to adhere to and multiply on various inert substrates (open surfaces, internal surfaces of water pipes or air ducts, materials, equipment, products, etc.) to form, with the recruitment of other micro-organisms, a biofilm or fixed cellular ecosystem. The biofilm on inert supports is fed and constantly maintained by micro-organisms transmitted by air, water, people or another inert support [BIO 600] .

Biofilm formation on an inert support generally involves three major stages (figure