Brewhouse-resident microbiota are responsible for multi-stage fermentation of American coolship ale

• Published in: PloS one 2012-04, Vol.7 (4), p.e35507
• Main Authors: Bokulich, Nicholas A, Bamforth, Charles W, Mills, David A
• Format: Article
• Language: English
• Subjects: Aerobic bacteria; Analysis; Bacteria; Bacteria - classification; Bacteria - genetics; Baking yeast; Beer; Beer - microbiology; Beer - standards; Biology; Breweries; Brewing; Community structure; Ecosystems; Fermentation; Food Microbiology; Food science; Genomes; Humans; Inoculation; Metagenome; Microbiology; Microbiota; Microbiota (Symbiotic organisms); Microorganisms; Molecular Typing; Phenols; Phylogenetics; Polymerase chain reaction; Polymorphism; Principal Component Analysis; Production controls; Production methods; Production processes; Quality standards; Restriction fragment length polymorphism; Saccharomyces cerevisiae; Wineries & vineyards; Yeasts; Yeasts - classification; Yeasts - genetics
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0035507

American coolship ale (ACA) is a type of spontaneously fermented beer that employs production methods similar to traditional Belgian lambic. In spite of its growing popularity in the American craft-brewing sector, the fermentation microbiology of ACA has not been previously described, and thus the interface between production methodology and microbial community structure is unexplored. Using terminal restriction fragment length polymorphism (TRFLP), barcoded amplicon sequencing (BAS), quantitative PCR (qPCR) and culture-dependent analysis, ACA fermentations were shown to follow a consistent fermentation progression, initially dominated by Enterobacteriaceae and a range of oxidative yeasts in the first month, then ceding to Saccharomyces spp. and Lactobacillales for the following year. After one year of fermentation, Brettanomyces bruxellensis was the dominant yeast population (occasionally accompanied by minor populations of Candida spp., Pichia spp., and other yeasts) and Lactobacillales remained dominant, though various aerobic bacteria became more prevalent. This work demonstrates that ACA exhibits a conserved core microbial succession in absence of inoculation, supporting the role of a resident brewhouse microbiota. These findings establish this core microbial profile of spontaneous beer fermentations as a target for production control points and quality standards for these beers.