Department of Food science, Food Microbiology.

This master project is part of a research project which deals with bacterial survival in low moisture environment. Salmonella has been known to persist for extended periods in dry environments e.g. more than years in places such as nut orchards (Uesugi et al. 2007) or in seeds. Many large international Salmonella outbreaks have been caused by long time stored, low water activity foods such as spices, nuts, peanut butter, chocolate, dried milk, toasted cereals etc.

Organic osmolytes are small solutes used by cells of numerous water-stressed organisms and tissues to maintain cell volume. These solutes may be amino acids and derivatives, polyols, sugars, methylamines, and more. Several of these compounds are naturally present in food matrices, but it is not well known how they interact with bacteria and to which degree they confer protection during drying and storage.

This master project will focus on the influence of specific osmolytes under controlled conditions on the survival of selected Salmonella spp from different environments. This will be investigated in a microtiter system both under aerobic and anaerobic conditions, as oxygen may be a critical factor in regard to survival. The influence will be tested using both classical and molecular microbiological techniques. Investigations using HPLC may be included to follow the intra- and extracellular concentrations of osmolytes during osmotic stress.

The project will be suitable for a 30 to 60 ECTS thesis

Skills needed include experience and precision in microbiological lab work  

Start: As soon as possible

For more information contact:

Susanne Knøchel (professor), e-mail: 

Nanna Christensen (ph.d student), e-mail: