Fungal diversity on brewery filling hall surfaces and quality control samples.

Breweries produce an increasing selection of beer and nonbeer beverages. Yeast and filamentous fungi may compromise quality and safety of these products in several ways. Recent studies on fungal communities in breweries are scarce and mostly conducted with culture-dependent methods. We explored fungal diversity in the production of alcoholic and nonalcoholic beverages in four breweries. Samples were taken for next generation sequencing (NGS) at the key contamination sites in 10 filling lines. Moreover, fungal isolates were identified in 68 quality control samples taken from raw materials, filling line surfaces, air, and products. NGS gave a comprehensive view of fungal diversity on filling line surfaces. The surface-attached communities mainly contained ascomycetous fungi. Depending on the site, the dominant genera included Candida, Saccharomyces, Torulaspora, Zygosaccharomyces, Alternaria, Didymella, and Exophiala. Sanger sequencing revealed 28 and 27 species of yeast and filamentous fungi, respectively, among 91 isolates. The most common species Saccharomyces cerevisiae, Zygosaccharomyces rouxii, and Wickerhamomuces anomalus were detected throughout production. Filling line surface and air samples showed the greatest diversity of yeast and filamentous fungi, respectively. The isolates of the most common yeast genera Candida, Pichia, Saccharomyces, and Wickerhamomyces showed low spoilage abilities in carbonated, chemically preserved drinks but could grow in products with reduced hurdles. Preservative resistant yeasts were rare, belonging to the species Dekkera bruxellensis, Pichia manschurica, and Zygosaccharomyces bailii. Penicillium spp. were dominant filamentous fungi. The results of this study help to evaluate spoilage risks caused by fungal contaminants detected in breweries.