Traditional lambic beer production takes place through wort inoculation with environmental air and fermentation and maturation in wooden barrels. These wooden casks or foeders are possible additional inoculation sources of microorganisms for lambic worts. To date, however, these lambic barrels have been examined only with culture-dependent techniques, thereby missing a portion of the microorganisms present. Moreover, the effects of the cleaning procedures (involving high-pressure water and/or fumigation) and the barrel type on the microbial community structures of the interior surfaces of wooden lambic barrels were unclear. The culture-dependent plating and culture-independent amplicon sequencing of swab samples obtained from the interior surfaces of different wooden casks and foeders used for traditional lambic beer production in Belgium revealed that the microbial compositions of these surfaces differed statistically throughout the barrel-cleaning procedures applied. At the end of the cleaning procedures, amplicon sequencing still detected fermentation- and maturation-related microorganisms, although only a few colonies were still detectable using culture-dependent methods. It is possible that some of the surviving microorganisms were missed due to the presence of many of these cells in a viable but not culturable state and/or engrained deeper in the wood. These surviving microorganisms could act as an additional inoculation source, besides brewery air and brewery equipment, thereby helping to establish a stable microbial community in the wort to diminish batch-to-batch variations in fermentation profiles. Furthermore, the microbial compositions of the interior barrel surfaces differed statistically based on the barrel type, possibly reflecting different characteristics of the lambic barrels in terms of age, wood thickness, and wood porosity.IMPORTANCEAlthough the coolship step is generally regarded as the main contributor to the spontaneous inoculation by environmental air of fresh worts for lambic beer production, it is known that microorganisms often associate with specific surfaces present in a brewery. However, knowledge about the association of microorganisms with the interior surfaces of wooden lambic barrels is limited. To clarify the role of casks and foeders as additional microbial inoculation sources, it was important to determine the influence of the barrel characteristics and the cleaning procedures on the microbial communities of the interior barrel surfaces. Moreover, this helped to elucidate the complex spontaneous lambic beer fermentation and maturation process. It will allow further optimization of the lambic beer production process, as well as the wooden-barrel-cleaning procedures applied.

European fermented meat products are prepared according to a wide variety of different recipes and processing conditions, which can influence their fermentative microbiota. However, due to the diverse processing conditions applied across Europe, it remained unclear to which degree bacterial heterogeneity can be encountered in commercially available fermented meat products and whether this is linked to their geographical origin. Therefore, the bacterial species diversity of 80 fermented meat products available in the Belgian retail, coming from five different countries, was investigated. It was also assessed how this related to the country of origin and the key processing parameters pH and salt concentration. The samples originated from Belgium, France, Germany, Italy, and Spain. In general, Southern European fermented meat products commonly had a higher pH, with their lactic acid bacteria (LAB) communities being represented by Lactobacillus sakei and with mostly Staphylococcus xylosus and Staphylococcus equorum governing over the coagulase-negative staphylococci (CNS) communities. Among these products, the Spanish variants showed a higher prevalence of S. equorum, whereas S. xylosus was the prevailing CNS species in most French and Italian fermented meat products. In contrast, Northern European fermented meat products were generally more acidified and showed a higher prevalence of Pediococcus pentosaceus in their LAB communities, whereas Staphylococcus carnosus represented the CNS communities. Non-parametric statistical tests indicated the impact of the geographical origin on the prevalence of the LAB and CNS species. The latter was likely due to the combination of differences in process technology as well as starter culture use.

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A total of 332 staphylococcal strains, mainly isolated from meat, were screened for antibacterial activity. Eighteen strains exhibited antibacterial activity towards species within the same genus. These antibacterial strains were further screened against Clostridium botulinum, to assess their potential as anticlostridial starter cultures for the development of fermented meat products without added nitrate or nitrite. Only Staphylococcus sciuri IMDO-S72 had the ability to inhibit all clostridial strains tested, whilst displaying additional activity against Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. Apart from their potential as bioprotective cultures, the staphylococcal collection was also screened for biogenic amine production, as these compounds may compromise food quality. To this end, ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was applied. A low incidence of biogenic amine production was found, with tyramine and β-phenylethylamine being the most prevalent ones. Concentrations remained relatively low (< 52 mg/L) after a prolonged incubation period, posing no or little threat towards food safety. Taken together, S. sciuri IMDO-S72 could serve as an interesting candidate for the bioprotection of fermented meats as it showed promising antibacterial activity as well as absence of biogenic amine production.

The bacterial communities that are established during natural meat fermentation depend on the processing conditions and the type of meat substrate used. Six pork samples of variable quality (reflected in pH values) and six less conventional meats (beef, horse, hare, wild deer, wild duck, and wild boar) were naturally fermented under controlled conditions in model systems. The development of lactic acid bacteria (LAB), coagulase-negative staphylococci (CNS), and enterobacteria was followed using culture-dependent techniques and (GTG)5-PCR fingerprinting of genomic DNA from the isolates obtained. Taken together, Latilactobacillus sakei was the most abundant LAB species, although Latilactobacillus curvatus was more manifest in high-pH pork. Within staphylococci, common species were encountered (i.e., Staphylococcus equorum, Staphylococcus saprophyticus, and Staphylococcus xylosus), although some atypical ones (i.e., Staphylococcus succinus) were also recovered. Within enterobacteria, Serratia spp. prevailed in more acidic pork batches and in beef, whereas Hafnia spp. prevailed in game meat fermentations. Enterobacterial counts were particularly high in fermentations with low acidity, namely for some pork batches, hare, wild duck, and wild boar. These findings should be considered when naturally fermented meat products are manufactured, as the use of game meat or meat with high pH can give rise to safety concerns.