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L 55
A new maltose/maltotriose transporter
[Saccharomyces eubayanustype
Agt1] in lager yeast and its
relevance to fermentation performance
Virve Vidgren 1, Jari Rautio 2, Laura Mattinen 2,
Brian Gibson 1, John Londesborough 1
1VTT Technical Research Centre of Finland, Espoo, Finland,
2Plexpress Oy, Helsinki, Finland
DESCRIPTION OF TOPIC:
Fermentation performance of lager yeast is
determined by uptake of fermentable sugar
in a low temperature environment. A new putative
maltose/maltotriose transporter gene
was identifi ed from lager strain WS34/70 and
suggested to be the Saccharomyces eubayanus
(Se) version of the Agt1 transmembrane
transporter in the hybrid lager yeast S. pastorianus
(S. cerevisiae x S. eubayanus). In the
present work, the transporter coded by this
putative AGT1 gene was characterized and
its relative activity at low temperature assessed.
Results showed that SeAGT1 encodes
a functional α-glucoside transporter with a
wide substrate range, including maltose and
maltotriose. The Se form of the transporter
derived from the cryotolerant S. eubayanus
species was found to be less sensitive to low
temperature conditions than the S. cerevisiae
form. Thus, SeAGT1 may have contributed to
the superior performance of lager yeasts in
low temperature fermentations compared to
ale yeasts.
Virve Vidgren
Virve Vidgren (PhD) is research scientist
working in the fi eld of Yeast Physiology and
Fermentations within VTT Bio- and chemical
processes. She has broad experience in yeast
genetics and physiology. One focus of her studies
has been transporters involved in uptake
of sugars during wort fermentations.
L 56
Development of the direct DNA extraction
method for rapid detection
of low concentrations of beer-spoilage
lactic acid bacteria
Masaki Shimokawa 1, Satomi Naito 1,
Kazumaru Iijima 2, Yasuo Motoyama 3,
Tomomichi oga 1, Koichi Harayama 1
1Asahi Breweries Ltd., Quality Control Center, Moriya, Japan,
2Asahi Breweries Ltd., Research and Development Laboratories
for Brewing, Moriya, Japan, 3Asahi Breweries Ltd.,
Nagoya Brewery, Nagoya, Japan
DESCRIPTION OF TOPIC:
We aimed to develop a rapid and highly sensitive
method for the detection of beer-spoilage
lactic acid bacteria (LAB) in beer, based on
polymerase chain reaction combined with the
direct DNA extraction method from the trapped
cells within the cellulose membrane by
using Barocycler. Barocycler is the device
making cycles of extreme high and ordinary
pressure conditions in a reaction vessel. These
pressure cycles are expected to enhance
the penetration of DNA extracting solution
into the matrix of membrane and disrupt
cells eff ectively. The detection limits of our
developed method was about 10^0-1 cells/
membrane, when Lactobacillus brevis was
suspended in from 300 ml up to 3000 ml of
beers. These results indicate that our direct
DNA extraction approach makes it possible to
apply larger sample volume than previous reports
without compromising recovery of DNA.
Taken together, our method was indicated to
be applicable to beers contaminated with low
concentrations of beer-spoilage LAB.
Masaki Shimokawa
Received a ME degree in Environmental Engineering
from Hokkaido University, Japan,
in 2008, where he majored in environmental
microbiology. He joined Asahi Breweries,
Ltd. in April 2008. Since September 2011, he
has been working on microbiological quality
assurance in breweries and developing the
detection technology of beer spoilage microorganisms
in Quality Control Center.
42
L 57
Evaluation of biofi lm composition
and maturation using realtime-PCR
Mathias Hutzler 1, Robert Riedl 1, Jennifer
Koob 1, Fritz Jacob 1
1TUM Weihenstephan, Research Center Weihenstephan,
Freising, Germany
DESCRIPTION OF TOPIC:
Biofi lms are a major source of microbial contamination
and hygienic risks within the brewing
environment. Biofi lms consist of diff erent
microbial fractions. Amongst other fractions
they can contain biofi lm starters, slime/EPS
forming bacteria, gram-positive beer spoiling
bacteria, strictly anaerobic gram-negative
beer spoiling bacteria and diff erent species of
yeast. In this study a modular PCR-Screening
assay was designed and evaluated to detect a
wide spectrum of bacteria and yeasts, which
are involved in the growth of biofi lms. The
quantitative evaluation of the diff erent microbial
fractions of the biofi lm enabled a classifi
cation of biofi lms into diff erent levels of maturation
and contamination risk. The identities
were linked with data about the organisms,
containing metabolic products, product risk
and typical locations. Additionally typical indicator
organisms for the biofi lm maturation
level and for subsequent product risk were
identifi ed.
Mathias Hutzler
Born in 1978 in Regensburg, Germany.
1999-2004 studies and graduation in Food
Technology and Biotechnology, TU München.
2004-2009 Scientifi c Assistant at the Chair
for Brewing Technology II, TU München. Topic
of doctoral thesis: Diff erentiation of industrial
and spoilage yeasts based on novel rapid
methods. Since 2009 head of the yeast center
and the accredited laboratory for brewing/
beverage microbiology at the Research Center
Weihenstephan for Beer and Food Quality,
TU München.