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Pellicle formation in ''Acetobacter tropicalis'' has been linked to a gene cluster (polABCDE), and disruption of these gene switched the cells from producing CPS (and pellicle formation) to producing EPS instead <ref name="Perumpuli"></ref>..
The presence of ethanol in concentrations of 1-4% encourages pellicle production in some strains of ''Acetobacter pasteurianus'' (although the presence of ethanol encourages pellicle formation, the amount of ethanol did not make a difference). In some strains of ''A. pasteurianus'', sugar encourages pellicle formation. It has been suggested that CPS production in ''Acetobacter'' is a function of stress tolerance by acting as a barrier around the cell that protects it from acetic acid in the environment. Strains that form a pellicle in the presence of ethanol and/or higher temperatures can fully ferment vinegar whereas those that do not create a pellicle perform poorly in comparison <ref name="Perumpuli"></ref>. ==Handling/Racking==Most brewers will advise that if it all possible, try not to disturb the pellicle too much when taking a sample, racking, or moving the fermenting vessel. If taking a sample or racking, gently pierce the top of the pellicle with the racking cane or wine thief. If the pellicle does break up, don't worry too much. It will usually reform if oxygen is still present in the headspace. While packaging the beer, try not to disturb the pellicle too much because clumps of the pellicle on the surface of the beer can fall back into solution when disturbed, and can then get transferred into the bottles or kegs. ==Pellicle Formation In Bottles== [[File:Pellicle bottle.JPG|thumb|Pellicle formation in a bottle a few days after packaging; courtesy of Dan Pixley]]Often a pellicle will form on the surface of the beer inside the bottle shortly after packaging. This is no different than the pellicle forming in the fermentation vessel, and presumably occurs because of the oxygen in the headspace of the bottle. The pellicle will eventually settle out either on it's own during aging, or when the bottle is refrigerated. Other than for aesthetics, there should be no concern if this happens.
==Scientific Terminology==
The importance of understanding this terminology becomes apparent when trying to research the topic of pellicles in beer. Currently they have not been studied much at all, whereas pellicles of dentistry and microbiology have been studied in depth, as well as biofilms. Thus, brewers should take care when researching scientific publications.
==Handling/Racking==
Most brewers will advise that if it all possible, try not to disturb the pellicle too much when taking a sample, racking, or moving the fermenting vessel. If taking a sample or racking, gently pierce the top of the pellicle with the racking cane or wine thief. If the pellicle does break up, don't worry too much. It will usually reform if oxygen is still present in the headspace. While packaging the beer, try not to disturb the pellicle too much because clumps of the pellicle on the surface of the beer can fall back into solution when disturbed, and can then get transferred into the bottles or kegs.
==Pellicle Formation In Bottles==
[[File:Pellicle bottle.JPG|thumb|Pellicle formation in a bottle a few days after packaging; courtesy of Dan Pixley]]
Often a pellicle will form on the surface of the beer inside the bottle shortly after packaging. This is no different than the pellicle forming in the fermentation vessel, and presumably occurs because of the oxygen in the headspace of the bottle. The pellicle will eventually settle out either on it's own during aging, or when the bottle is refrigerated. Other than for aesthetics, there should be no concern if this happens.
==Images==