Emergence of New Spoilage Microorganisms in the Brewing Industry and Development of Microbiological Quality Control Methods to Cope with This Phenomenon - A Review

Until 30 years ago, only a limited number of bacterial and wild yeast species had been recognized as beer spoilers. However, the number of spoilage species have been rapidly increasing since then, reaching approximately 30 species for traditional beer categories. One trend is the continual emergence of new beer spoilage lactic acid bacteria. Many of these novel beer spoilage species are almost exclusively found in the brewing environments and are considered as beer-associated microorganisms. The second trend is the rise of strictly anaerobic beer spoilage bacteria, includingPectinatusandMegasphaera. Currently, close to 10 strictly anaerobic beer spoilage species have been reported. As a countermeasure, species-specific PCR systems have been adopted in breweries, and continually modified to keep up with the increasing number of beer spoilage species. Nevertheless, the circumstances are changing because of the rising trend of non-traditional beverages, as well as the rising use of non-traditional ingredients, in the brewing industry. These non-traditional beverages include non-alcoholic beers and flavored low alcoholic beverages, and spoilage species for these microbiologically unstable products are dramatically increasing in number. The conventional species-specific PCR can only handle the identification of 20-30 species of microorganisms, while novel methods that allow for a much broader microbial identification, such as DNA sequencing, are becoming more necessary. A few brewers are already evaluating the potential quality control applications of inexpensive third generation DNA sequencing technologies with the brewing industry.