Microbiology Session
Jordyn Bergsveinson, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
Co-author(s): Vanessa Pittet and Barry Ziola, University of Saskatchewan, Saskatoon, SK, Canada
ABSTRACT: Although the unique chemical and physical
composition of beer provides an incredibly inhospitable environment for
bacterial growth, lactic acid bacteria (LAB) frequently survive in and
spoil beer. The presence of contaminating bacteria therefore poses a
great threat to the brew quality and economic success of a brewery. Pediococcus and Lactobacillus
are common genera of LAB isolated from spoiled beer; however, not all
isolates of a given species in either genus can grow in beer. This
indicates there is genetic specialization in beer-spoiling organisms
such as Pediococcus claussenii ATCC BAA-344T (Pc344NR; non-ropy) and Lactobacillus brevis
BSO 464 (BSO 464), both of which are capable of flourishing in a beer
environment. Despite the evident genetic adaptations of beer-spoilage
LAB, very few genes have been found to correlate with the beer-spoiling
ability of an organism. To investigate the role of several putative
beer-spoilage related genes within each organism in relation to growth
in beer, quantitative reverse transcriptase polymerase chain reaction
(qRT-PCR) was utilized. RNA was extracted from both Pc344NR and BSO 464
cultures at mid-logarithmic growth in both beer and non-beer
environments and then converted to cDNA and subjected to qRT-PCR
analysis. In order to accurately assess differential gene expression in
the beer environment, appropriate internal control genes are needed to
normalize the experimental setup for sample variation and experimental
error. As such, expression stability (in both growth conditions) of 12
candidate normalization genes was performed and analyzed with the
application geNorm. Subsequently, cDNA samples were analyzed to
determine the expression levels of the putative beer-spoilage related
genes hitA, horA, horB, horC, and bsrA.
Using this methodology, we now have a better understanding of the role
these genes play during growth in beer for our two LAB isolates. It is
anticipated that this work will be extended to include qRT-PCR analysis
of possible beer-spoilage related genes in a broad range of LAB with the
intent to definitively identify genes that can serve as genetic markers
for assessing bacterial beer-spoilage potential.
Jordyn
Bergsveinson received a B.S. degree (with honors) in microbiology and
immunology in 2011 from the University of Saskatchewan. She is currently
working toward completing an M.S. degree in health sciences through the
College of Medicine at the University of Saskatchewan, under the
supervision of Barry Ziola. Her research topic and area of interest
concerns the genetic and molecular analysis of beer-spoiling
microorganisms.
VIEW PRESENTATION 176
