Daniel Gerhards
Pall GmbH

MIKROBIOLOGIA
Słowa kluczowe: beer, qPCR, GeneDisc, bacteria, yeast

Introduction

Spoilage is a major concern for the brewing industry who values quality product delivery and brand protection. As a result, most breweries have implemented traditional culture methods which are time-consuming and display weak sensitivity and specificity. To address the customer’s need for a rapid method to monitor spoilage, Pall® offers RT-PCR-based methods using the GeneDisc system for rapid and specific detection of major beer spoilage bacteria and yeasts.

Material & Methods

Spoilers are concentrated by filtration through 0.45 μm polyethersulfone membrane, or by centrifugation for unfilterable samples. Optionally, samples are enriched in selective broths for detection of spoilage bacteria and yeasts. Sample preparation is based on microbial lysis by sonication and/or heating, then PCR analyses are performed with 3 different GeneDisc Plates.

The GeneDisc Beer Spoilage Bacteria enables the simultaneous detection of 22 beer spoilage bacteria. The GeneDisc for Yeast Screening enables detection of spoilage associated yeasts and the GeneDisc Yeast ID is designed to detect the 7 major spoilage yeast genera and 5 major associated species. Results Specificity of the PCR assays was demonstrated by exclusivity and inclusivity tests from 274 and 61 pure cultures, for testing the 12 yeast targets and 22 bacteria targets, respectively.

The detection of as few as 1 spoilage bacteria or yeasts per mL of beer sample was achievable in less than 3 hours thanks to sample preparation from large volume sample (45 – 500 mL). After enrichment for 24 – 72 hours, the GeneDisc methods were validated with less than 1 cell / sample.

Conclusions

The GeneDisc technology provides a range of flexible methods enabling to guarantee absence of spoilage bacteria or yeast in beer samples or the direct monitoring of as few as 1 cell per mL in less than 3 hours. This technology can be easily implemented in quality control laboratory for monitoring spoilage all over the brewing process.