title: Microbial diversity and metabolite composition of Belgian red-brown acidic ales.
abstract: Belgian red-brown acidic ales are sour and alcoholic fermented beers, which are produced by mixed-culture fermentation and blending. The brews are aged in oak barrels for about two years, after which mature beer is blended with young, non-aged beer to obtain the end-products. The present study evaluated the microbial community diversity of Belgian red-brown acidic ales at the end of the maturation phase of three subsequent brews of three different breweries. The microbial diversity was compared with the metabolite composition of the brews at the end of the maturation phase. Therefore, mature brew samples were subjected to 454 pyrosequencing of the 16S rRNA gene (bacteria) and the internal transcribed spacer region (yeasts) and a broad range of metabolites was quantified. The most important microbial species present in the Belgian red-brown acidic ales investigated were Pediococcus damnosus, Dekkera bruxellensis, and Acetobacter pasteurianus. In addition, this culture-independent analysis revealed operational taxonomic units that were assigned to an unclassified fungal community member, Candida, and Lactobacillus. The main metabolites present in the brew samples were L-lactic acid, D-lactic acid, and ethanol, whereas acetic acid was produced in lower quantities. The most prevailing aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, and ethyl octanoate, which might be of impact on the aroma of the end-products.
authors.affiliation: Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium. Electronic address: Isabel.Snauwaert@Ugent.be.
authors.forename: Isabel
authors.initials: I
authors.lastname: Snauwaert
authors.affiliation: Department of Data Analysis, Ghent University, Henri Dunantlaan 1, B-9000 Ghent, Belgium.
authors.forename: Sanne P
authors.initials: SP
authors.lastname: Roels
authors.affiliation: Laboratory of Pharmaceutical Biotechnology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Van Nieuwerburgh
authors.affiliation: Laboratory of Biochemistry and Brewing, Faculty of Bioscience Engineering, Ghent University, Valentin Vaerwyckweg 1, B-9000 Ghent, Belgium.
authors.forename: Anita
authors.initials: A
authors.lastname: Van Landschoot
authors.affiliation: Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: De Vuyst
authors.affiliation: Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Vandamme
mesh_terms: D001419:Bacteria / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D001515:Beer / Q000032:analysis / Q000382:microbiology*; D001530:Belgium; D044822:Biodiversity; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D015003:Yeasts / Q000235:genetics / Q000502:physiology*
chemical_list: D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D000431:Ethanol
keywords: 454 pyrosequecing; Beer; Metabolite target analysis; Microbial diversity analysis