Thursday, 25 April 2013

How Salmonella uses biofilm to survive in hostile environments


New research has shown that in addition to protecting Salmonella from heat-processing and sanitizers such as bleach, biofilms preserve the bacteria in extremely dry conditions, and again when the bacteria are subjected to normal digestive processes.

The research has shown that in moist conditions, Salmonella thrive and reproduce abundantly. If thrust into a dry environment, they cease to reproduce, but turn on genes which produce a biofilm, protecting them from the detrimental environment.

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Researchers tested the resilience of the Salmonella biofilm by drying it and storing it in dry milk powder for up to 30 days. At various points it was tested in a simulated gastrointestinal system. Salmonella survived this long- term storage in large numbers but the biofilm Salmonella were more resilient than the free-floating cells treated to the same conditions.

The bacteria's stress response to the dry conditions also made it more likely to cause disease. Biofilms allowed the Salmonella to survive the harsh, acidic environment of the stomach, increasing its chances of reaching the intestines, where infection results in the symptoms associated with food poisoning.


The research was undertaken at Virginia Tech. The study has been published in the  International Journal of Food Microbiology.

Posted by Tim Sandle

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