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==Biofilms==
Many microorganisms can form ''biofilms'' which is defined as a community of cells of one or more species that are attached to each other and/or a surface and are embedded in a matrix of extracellular polymeric substances (EPS), including . EPS consists of polysaccharides and proteinsthat are produced by the microorganisms and expelled out of the cells, similar to a [[Pellicle|pellicle]]. Biofilms allow microbes to survive less vigorous cleaning and sanitizing regiments and chemicals and has become a concern in the food industry as well as in the brewing and winemaking industries <ref>[https://onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12087 The Paradox of Mixed‐Species Biofilms in the Context of Food Safety. Iqbal Kabir Jahid and Sang‐Do Ha. 2014.]</ref>. Biofilms most often form in the packaging system somewhere, but can also be found on side rails, wearstrips, conveyor tracks, drip pans, and in-between chain links <ref name="storgards_2000" />.
Bacteria and yeast form a biofilm in two stages, which are determined by a number of variables. In the first stage, the microbes remain in their [http://www.dictionary.com/browse/planktonic|"planktonic"] form (floating around in the liquid), but they begin to adhere on surfaces and to each other as those surfaces. Other species of microbes can also be adhered to during this phase. The second stage is where the microbes start producing exopolysaccharides (EPS) which helps them bind together in a matrix, along with any available proteins and exopolymers produced by the bacteria. A large portion of biofilms is actually water (80-80%) as this allows the microbes to remove waste and consume nutrients. This matrix helps the microbes resist antibiotics, UV radiation, and cleaning chemicals. Gene exchange also occurs more frequently. At the end of this second stage, the microbes become attached to surfaces in such a way that is permanent without the use of cleaning chemicals. This is known as the microbe's [http://www.dictionary.com/browse/sessile|"sessile"] form (immobile). Bacteria in this form continue to multiply, and upon maturation of the biofilm, eventually, planktonic cells begin to be produced and released from the biofilm to find new homes. They also display different phenotypes, which might contribute to their ability to resist cleaning chemicals. Rough surfaces, scratched surfaces, jagged edges, and pores are more prone to biofilm formation due to the higher surface area. Hydrophobic surfaces, such as Teflon and other plastics, are more prone to biofilm formation than hydrophilic surfaces (glass and stainless steel). Nitrile butyl rubber (NBR) was found to inhibit biofilm formation when new, but as the material breaks down biofilms are able to grow <ref>Biofilms in the Food and Beverage Industries. P M Fratamico, B A Annous, N W Guenther. Elsevier, Sep 22, 2009. Pp 4-14.</ref>. Biofilm formation is strain specific rather than species specific; some strains can form thicker biofilms than others within the same species and faster, and some strains of lactic acid species are not good biofilm producers. Full biofilms can form within 2-4 days for some strains, while 10 days is required for significant biofilm formation in other strains. For example, one strain of ''Lactobacillus brevis'' isolated from draft beer did not form any biofilm, while another strain of ''L. brevis'' tested was a strong biofilm producer. Similar results were observed for ''Brettanomyces'' strains. In general, mixed cultures form stronger biofilms than single cultures. The presence of soil (biological residue) encourages biofilm formation <ref name="Wirtanen_2001" />. The presence of sweeteners or sugar also encourages the formation of biofilms. In one study (Storgårds 2006), biofilm forming species were found to begin attaching themselves to brand new sterile stainless steel surfaces within 2-12 hours after the new equipment was used for production <ref name="Storgårds_2006">[https://www.researchgate.net/publication/279707988_Microbial_attachment_and_biofilm_formation_in_brewery_bottling_plants Microbial attachment and biofilm formation in brewery bottling plants. Erna Storgårds, Kaisa Tapani, Peter Hartwall, Riitta Saleva & Maija-Liisa Suihko. 2006. DOI: https://doi.org/10.1094/ASBCJ-64-0008.]</ref>.