Changes

Pellicle formation by microbes found in sour beer such as ''[[Brettanomyces]]'' and ''[[Lactobacillus]]'' has not been widely studied. One 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, 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 from 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>.