Brewhouse-Resident Microbiota Are Responsible for Multi-Stage Fermentation of American Coolship Ale

Abstract

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.

Microbial biogeography of wine grapes is conditioned by cultivar, vintage, and climate

“…However, recent advances in massively parallel, short-amplicon sequencing technologies have launched a breakthrough in microbial ecology studies of wine-and foodfermentation systems (14,(21)(22)(23)(24)(25)(26)(27), putting hitherto untenable ecological questions within reach.…”

Metagenomics insights into food fermentations

“…In other studies, the microbiota was related to raw material origin (Bokulich et al ., 2014a; Rizzello et al ., 2015) or quality (Dolci et al ., 2014; O'Sullivan et al ., 2015; Alessandria et al ., 2016), as well as to development of flavour‐impact compounds (De Pasquale et al ., 2014a, 2016; De Filippis et al ., 2016a). Moreover, food‐related environments were found to harbour a resident microbiota, beneficially involved in dairy (Bokulich and Mills, 2013a; Stellato et al ., 2015; Calasso et al ., 2016), alcoholic (Bokulich et al ., 2012a, 2014b) and sourdough (Minervini et al ., 2015) fermentations, although the presence of potential spoilers was also emphasized in some cases (Bokulich et al ., 2015a; Stellato et al ., 2015). …”

Saccharomyces and Non-Saccharomyces Starter Yeasts

“…American coolship ale beer is another example of spontaneous fermentation, where the process can be divided into various steps: Enterobacteriaceae and oxidative yeast in the irst phase, which are replaced by Saccharomyces spp. and Lactobacillales, and then Dekkera bruxellensis, which prevails through the inal process [33]. Other nonconventional beers, such as Tchapalo, are brewed using C. tropicalis and S. cerevisiae cultures that have been selected for their fermenting of sorghum wort.…”