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An often asked question by homebrewers is can a contaminating or wild caught microbe be identified based on the appearance of a pellicle. This is a difficult exercise for a few reasons.
# There is very little research on pellicles when it comes to beer fermentation, so saying anything definitive about them is difficult, and identifying one or more microbes that created a pellicle based on what the pellicle looks like is currently impossible.
# The number and size of bubbles in a pellicle is largely dependent on the amount of trapped CO2, and thus is not an identifying feature.
# 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? Does beer composition (more or less protein content, residual sugars, etc.) affect pellicle appearance? 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.