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added a section of microbe identification based on pellicle appearance
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>.
===Identification in Contaminated Beers===
An often asked question by homebrewers is can a contaminating microbe be identified based on the appearance of a pellicle. This is an impossible exercise for a few reasons.
# While different strains of the same species of microbe (at least in ''acetobacter'') can create different types of polysaccharides that make up the pellicle, their chemical make up is more or less very similar.
# Numbers and size of bubbles in a pellicle is created by trapped CO2, and thus is not an identifying feature.
# Scientific research on pellicle formation in beer is currently next to none.
# The factors that cause pellicle formation are not well understood. Oxygen is said to cause pellicle formation, but how, why, and in what species is not known. Does more oxygen create a thicker pellicle? If so, for what species does this apply to? The lack of answers to these questions and others imply that environmental factors are also not helpful in identifying what species of microbe produced a pellicle.
# Identification of microbes under a microscope based on cell morphology alone is not enough to be certain of that identification, let alone attempting to identify microbes based on a visual "macro-level" formation such as a pellicle.
# DNA analysis of a microbe is the only way to truly reliably identify the species of a microbe.
==Handling/Racking==