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===Acetobacter===
Pellicle formation by microbes found in sour beer such as ''[[Brettanomyces]] '' and ''[[Lactobacillus]] '' has not been closely widely studied. HoweverOne report by De Roos et al. (2018) reported that in lambic casks that were studied, a pellicle formed at around 6 months into spontaneous fermentation. This pellicle formation was attributed to by ''Brettanomyces'' and oxidative yeasts, we and this corresponded with a decline in acetic acid bacteria populations. The researchers concluded that the formation of the pellicle by yeasts could be a defense that helped reduce the competition of acetic acid bacteria <ref name="De_roos_AAB_2018">[https://journals.asm.org/doi/10.1128/AEM.02846-17 Temporal and Spatial Distribution of the Acetic Acid Bacterium Communities throughout the Wooden Casks Used for the Fermentation and Maturation of Lambic Beer Underlines Their Functional Role. ASM Journals. Applied and Environmental Microbiology. Vol. 84, No. 7. DOI: https://doi.org/10.1128/AEM.02846-17.]</ref>. We may also be able to glean some insight from studies done on ''Acetobacter'' pellicle formation during vinegar production.
''Acetobacter spp.'' produce homo and heteropolysaccharides (polysaccharides consisting of one type of sugar or more than one type of sugar, respectively <ref>[http://www.britannica.com/science/heteropolysaccharide Heteropolysaccharide. Encyclopedia Britannica. Retrieved 09/05/2015.]</ref>) that attach to the surface of the cells (capsular polysaccharides - '''CPS'''), as well as polysaccharides that are secreted into the medium in which they live (extracellular polysaccharides, or exopolysaccharides - '''EPS'''). CPS is the mechanism that allows pellicle formation in ''Acetobacter'' as the cells tightly associate to one another via CPS <ref name="Perumpuli"></ref>.