Fungal diversity on brewery filling hall surfaces and quality control samples

Abstract

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.

Repurposing brewery contaminant yeast as production strains for low‐alcohol beer fermentation

“…3.1 | Phenotypic screening of fungal brewery isolates for brewing-relevant traits A total of 56 yeast strains, previously isolated from industrial brewery environments (Sohlberg et al, 2021), were screened for various brewing-relevant phenotypes. Among the strains were 18 different species from 10 genera, and the isolation environments included brewery air, brewery surfaces, raw materials and spoiled products.…”

“…A recent survey of the microbiota in multiple breweries yielded a large collection of fungal isolates (Sohlberg et al, 2021). While a broad microbiota may typically be seen as a negative in an industrial brewery, we wanted to turn this into a positive.…”

Analysis of the bacterial and fungal populations in South African sorghum beer (umqombothi) using full-length 16S rRNA amplicon sequencing

“…Tremellomycetes are often isolated from cereal grains such as wheat, rice, maize, and sorghum, and may be found in the mucosal surfaces of approximately 1–10% of the healthy human population (Shoff and Perfect 2021 ). However, interestingly, they have been the dominant class in some wineries and breweries (Sohlberg et al 2022 ). Groups within this class may be extremely harmful or beneficial to humans (Weiss et al 2014 ).…”

Use of hop extract in the biotechnology of kefir beverage

“…It is likely that this effect was also caused by "wild" yeasts that developed on the surface of hop cones, which can inhibit the development of moulds. E. Sohlberg et al (2022) showed that "wild" yeast can proliferate during the initial phases of fermentation, outnumbering other species of microorganisms, including lactic acid bacteria, which are producers of lactic acid. These results confirm the assumption made.…”

“…Control sample 1 (C) was already unfit for consumption on Day 6 of storage. Yeasts have a higher resistance to lactic acid than other microorganisms, which allows them to grow dominantly (Sohlberg et al, 2022). As a result, the shelf life of fermented dairy products is extended.…”