Download Bacteria stress responce to high pressure processing

Bacteria stress response to
high pressure processing
Tine Bergitte Heggernes
Supervisor: Nadav Skjøndal-Bar
Project with Nofima – Måltidets Hus, Stavanger
Project Autumn 2013, Tine Bergitte Heggernes
Motivation
Listeria monocytogenes
Tine Bergitte Heggernes
Objective and methodology
Objective
• Doing a literature study on bacteria stress response to high pressure
processing (HPP).
• The bacteria response - change of gene expressions and mechanisms
in the cell when stressed.
Methodology
• Using experimental data done with HPP at 400 Mpa and 600 Mpa
with Listeria contaminated food
• Find vital HPP affected mechanisms  Genes activating these
mechanisms  Determination of most significant genes 
Comparing genes with regulation from other environmental stresses
 Proposing the most pressure specific genes
Bacteria stress responce to high pressure processing
Results and conclusion
HPP induced changes
• Many genes
expressed as a
response to HPP
• Expression change higher at
400MPa than 600 Mpa  less
developed response systems for
higher pressures.
Tine Bergitte Heggernes
The 7 most pressure specific genes
Category
Gene no
Fold change
400 Mpa
Fold change
600 Mpa
Salt
Acid
General
stress resp.
lmo1699
26,092
5,036
x
x
lmo0713
23,736
2,639
x
x
Cold - &
heatShock
lmo0292
-16,499
-8,018
x
Translation
lmo2656
10,660
6,078
x
lmo1785
9,161
6,353
lmo2507
14,644
35,737
x
x
lmo0584
-6,332
-5,050
x
x
Membrane
Tine Bergitte Heggernes
Heat
x
x
Cold
Futute work – Master thesis
• Conduct HPP experiments
• Develop models which predicts bacteria inhibition from high pressure
processing
Tine Bergitte Heggernes