A study by DVM Annukka Markkula and colleagues showed that DEAD-box RNA helicases have a marked role in growth of Listeria monocytogenes under heat, alkali, ethanol, and oxidative stress conditions. The study conducted in Professor Hannu Korkeala’s research group was published in valued Applied and Environmental Microbiology journal.

Appl Environ Microbiol 2012, 78:6875-6882.

Markkula A, Lindström M, Johansson P, Björkroth J and Korkeala H.

Department of Food Hygiene and Environmental Health, University of Helsinki

Roles of four putative DEAD-box RNA helicase genes in growth of Listeria monocytogenes EGD-e under heat, pH, osmotic, ethanol and oxidative stress conditions

In the study the growth of single DEAD-box RNA helicase gene deletion mutant strains were examined under heat, acid, alkali, osmotic, ethanol and oxidative stress conditions. The growth of one of the deletion mutant strains was restricted under 3.5% ethanol compared to that of the wild-type L. monocytogenes EGD-e strain. The maximum growth temperature of the mutant strain was increased by 0.6˚C. The growth of another mutated strain was impaired at 42.5˚C, and restricted under pH 9.4 and in 5 mM H₂O₂. Deletion of either of two remaining DEAD-box RNA helicase genes had no effect on the growth of L. monocytogenes under any growth condition examined.

A previous study by Annukka Markkula and colleagues has shown that DEAD-box RNA helicases have a marked role in growth of L. monocytogenes under cold stress. The importance of DEAD-box RNA helicases in cold stress tolerance in other organisms has also been reported. The role of these proteins in other stresses is almost unknown. The DEAD-box RNA helicases are found in most living organisms and are involved in various aspects of RNA metabolism from transcription to RNA decay. The functions of helicases under various stresses are unknown.

The research was carried out at the Finnish Centre of Excellence in Microbial Food Safety Research and supported by the Finnish Graduate School on Applied Bioscience and the Walter Ehrström Foundation.

MSc Astrid de Haan academic dissertation is presented, with the permission of the Faculty of Veterinary Medicine, Univerity of Helsinki, for public examination in Auditorium Walter (Agnes Sjöbergin katu 2), Helsinki on 28th of September 2012.

Title of thesis is  “Molecular typing and source attribution of Finnish Campylobacter jejuni isolates” and it belongs to the field of environmental health.

The opponent is professor Dr. Birgitta Duim (Utrecht University, Netherlands) and the custos is professor Marja-Liisa Hänninen.

An electronic version of the dissertation.