Sabine Mueller (1); (1) Doehler GmbH, Darmstadt, Germany

Food Safety

The detection of microorganisms using rapid methods, like PCR or real-time PCR, have gained importance in a brewery’s quality control. Although these methods permit fast and reliable detection of beer spoilers, the cultural enrichment of these samples is still crucial, especially for slow-growing microorganisms. A suitable enrichment medium should induce fast microbial growth. We demonstrate a new culture medium, NBB-PCR broth, with an optimized nutrient composition for enrichment of beer-spoiling microorganisms (within 48 hr), allowing optimal detection with PCR or real-time PCR. The aim was to develop a fast, universal enrichment medium for all relevant beer spoilers that is compatible with all common PCR detection methods and sample types arising in a brewery to ensure reliable results. The new broth was tested with the strains Lactobacillus brevis, Lactobacillus lindneri, Pediococcus damnosus and Pectinatus frisingensis (100 cells/mL, n = 3). Samples of filterable beer, cloudy beer, pitching yeast and cropped yeast (n = 3 each) were spiked with 100 cells/sample of the respective microorganism. After incubation at 28°C, samples were analyzed with four real-time PCR systems, as well as a novel PCR-based lateral flow detection system. The NBB-PCR broth enrichment medium was compatible with all tested PCR or real-time PCR systems, with no false positive results or PCR inhibition observed. After 48 hr of enrichment, all tested microorganisms reached reliable detection levels or showed significant reduction in Ct values. L. brevis and even slow-growing L. lindneri were already detectable after 24 hr (by one of the tested PCR systems). NBB-PCR broth is a reliable, ready-to-use enrichment medium that allows PCR or real-time PCR detection of beer spoilers (in 48 hr), as demonstrated with four differing test strains. NBB-PCR broth’s compatibility with all market-relevant PCR systems enables a dramatic decrease of the detection time and enables faster product release in breweries.

Sabine gained her Ph.D. degree in biochemistry at the Technical University of Darmstadt. In the beginning of her career she started as a sales representative for molecular biology products at Perkin Elmer in Switzerland. She then worked in several positions in product management and corporate strategy at the molecular diagnostics company QIAGEN GmbH. Since then she has taken responsibility for the industrial microbiology business of Biotest AG. Through the acquisition of Merck Millipore, she took over the product management leadership role for the dehydrated culture media of the Biomonitoring business unit. Since August 2014, Sabine has worked as the head of product management and sales for the ready-to-use culture media portfolio at Döhler GmbH.