Acetic acid bacteria (AAB) are often considered a threat of the past because today’s equipment allows to perform post-fermentation processes under greatly reduced level of oxygen. This paper deals with the current importance of AAB in brewing. The risk of contamination as well as functional role in spontaneously fermented sour beers is reviewed. The main harmful effect of AAB lies in the direct spoilage of draft beer and formation of biofilms, most often in dispensing systems. On contrary AAB seems to be indispensable in the case of sour beer production. A key issue of AAB in brewing environment is their (early) detection and identification. Therefore, part of this study is devoted to both the latest sophisticated methods and also those of traditional cultivation. which are still prevalent in operating laboratories due to their cost and easy implementation. Finally, the experimental and pictorial material is added as a guide for operations that have less experience with AAB.

In recent decades many changes have been adopted in the fungal nomenclature, including the names of yeasts, to achieve a more natural and uniform systematics. The use of one correct name is essential for communication, the search for new knowledge, research studies or business purposes not only in the brewing branch. Nevertheless, how can such rapid progress be followed? The paper attempted to briefly explain the reasons for immense changes that have occurred in the taxonomic and nomenclatural system mainly as a result of modern molecular findings. The process of reclassification is demonstrated on a group of selected contaminants currently detected in Czech beers or breweries. This article presents several online databases that document the ongoing changes and make it easy for experts from various fields to find valid names.

The aim of the long-term preservation of cells, tissues and organs is to maintain their cellular structures and biological functions for as long as possible. Cryopreservation is a process where biological material is stored and preserved at very low temperatures. However, freezing and thawing processes can cause irreversible cell damage, which is related to formation of ice crystals, osmotic stress, accumulation of reactive forms of oxygen, etc. Therefore the cell viability depends mainly on the freezing rate, the composition of the cryoprotective medium as well as on the thawing rate. Using a suitable cryoprotective medium can increase the viability rate of the yeasts after “revitalization“. Appropriate pre-cultivation before freezing also plays an important role. These facts show that cell freezing and thawing processes must be controlled to avoid cell damage.

The growth of 7 strains belonging to the order of Enterobacterales, represented by the species of Citrobacter Freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Obesumbacterium proteus, Rahnella aquatilis, Raoultella terrigena, Serratia marcescens and Shimwellia pseudoproteus, was monitored on selected cultivation media. Three types of agars - Endo, MacConkey and Chromocult Coliform agar together with two incubation temperatures of 28 and 37 °C were tested under aerobic conditions. The aim of the study was to detect such essential enterobacteria harmful to beer that cannot be proven at 37 °C, which is the temperature usually used in operational laboratories in breweries. Our results showed that most of the tested strains of enterobacteria were able to grow at 28 °C on all selected types of agar. The exception was just the representatives detection of which is problematic at 37 °C. Nevertheless, a little or no growth was always observed on just one of the tested media.