Technical Session 18: Microbiology II Session
Robert Riedl, Research Center Weihenstephan for Brewing- and Food-Quality,TU Muenchen, Freising, Germany
Co-author(s): Jennifer Koob, Mathias Hutzler, and Fritz Jacob,
Research Center Weihenstephan for Brewing and Food Quality, TU Muenchen,
Freising, Germany
ABSTRACT: Biofilms are a serious problem in breweries and
beverage bottling plants. Biofilms are associations of various species
of bacteria, yeasts, and molds. In contrast to planktonic
microorganisms, a layer of extracellular substances protects the cells
in biofilms, which makes them much more resistant against cleaning and
disinfection solutions. Most biofilm starter organisms, such as acetic
acid bacteria (AAB) or Enterobacteriaceae, are considered to not
be product spoiling. For this reason, most breweries do not use
cultivation media that are designed to detect them. Therefore a biofilm
will not be detected until product spoiling organisms colonize it.
Additionally, established cultivation media methods such as the NBB-B-AM
swab test, according to Prof. Back (1994), do not specify the
associated organisms. The composition of the associated organisms is
very important for evaluation of the level of maturity and potential
product spoiling risk of biofilms in breweries or beverage plants. The
rather long incubation time of 5–14 days for nutrition media tests is
another disadvantage. With molecular biological screenings, the
cultivation time can be reduced to 3 days using real time-PCR systems to
detect different target fractions of microorganisms. Most commercial
real time-PCR kits, established in brewing microbiology, focus on the
detection of beer spoiling bacteria. In this study a modular
PCR-screening assay was designed and evaluated to detect a wide spectrum
of bacteria and yeasts involved in the growth of biofilms. The first
screening step detects product specific, defined groups of organisms
that can be used as indicator organism groups for the state of maturity
in the biofilm development. The second step identifies the organisms
within the groups. The identified organisms were linked with data about
the organisms, containing metabolic products, product risk, and typical
locations. Maturity, as well as the potential for product spoiling of
the biofilm, can be measured by typical indicator organisms detected
using the real time-PCR screening system.
Robert Riedl was born
in 1983 in Munich. He studied brewing and beverage technology at the
Technische Universität München and graduated with a Dipl.-Ing. degree in
2011. Since July 2011 he has been a scientific assistant at the
Research Center Weihenstephan for Brewing and Food Technology and is
working on biofilm development in beverage plants.
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