The liquid equivalent of universal beer agar, designated universal beer liquid medium, and its beer-free equivalent, universal liquid medium (UL), were equally effective in demonstrating bacterial contamination in 120 of 200 samples from different stages of a commercial brewing process. Growth of the contaminants after 3 days was consistently more luxuriant in the UL medium. A yeast-water substrate medium failed to reveal many contaminants detected with UL in 392 samples from three breweries and revealed only a few not detected with UL. The use of UL and a lactose-peptone medium, with microscope examination of the media for bacterial growth, permitted detection of 93% of the known contaminants compared to 87% detected with UL alone; this combination or universal beer liquid medium plus lactose-peptone medium can therefore be recommended for the detection of bacterial contaminants in brewery samples. Bacterial contamination of pitching yeasts appeared to be a particular problem in the breweries investigated.
CITATION STYLE
Van Vuuren, H. J. J., Louw, H. A., Loos, M. A., & Meisel, R. (1977). Procedures involving liquid media for detection of bacterial contamination in breweries. Applied and Environmental Microbiology, 33(2), 246–248. https://doi.org/10.1128/aem.33.2.246-248.1977
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