Friday, June 14, 2013


Salmonella is a deadly pathogenic bug which has contributed to thousands of human death through consumption of contaminated foods, mostly in the US. Its potential for food poisoning is well known and extensively documented. There are hundreds of food poisoning episodes reported every year from all over the world from this food pathogen, in spite of pre-emptive precautions exercised by the industry. It has now been discovered that this monstrous bug has the capacity to defy every destruction technology man has known and it is spreading its tentacles far and wide affecting even dry foods with no moisture for survival! According to new studies Salmonella has acquired this new capability to resist severe processing condition because of a strange phenomenon called biofilm formation. Such biofilms containing these pathogens behave like a cocoon protecting them from harsh environment like high heat or high acidity! Here is a commentary on this new findings with far reaching implications. 

"Over the past five years, more than 900 Salmonella-related illnesses have been linked to dried foods such as nuts, cereals, spices, powdered milk and pet foods. Those foods were previously believed to have been safe from the bacteria, as their dry nature helps halt the growth of bacteria and other microbes. "Most people expect to find Salmonella on raw meats but don't consider that it can survive on fruits, vegetables or dry products, which are not always cooked," Ponder said. Salmonella typically thrive and reproduce abundantly in moist conditions, the researchers said. In dry conditions, they cease reproduction, but activate genes which produce biofilms, thus protecting them from the harsh conditions. "Researchers tested the resilience of the Salmonella biofilm by drying it and storing it in dry milk powder for up to 30 days," the university explained. "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," they added. "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 researchers believe that their work could help the US Food and Drug Administration (FDA) shape federal regulations by emphasizing the need for a new strategy to reduce biofilm formation on equipment. With luck, those strategies, along with improved sanitation techniques, will hopefully decrease the likelihood of another widespread Salmonella outbreak in the US".

Microbiologists are already familiar with the ability of some of the bugs to sporulate, how these spores are resistant to destruction under most severe heat treatment and the technology of Tyndalization involving serial high temperature treatment was specifically developed to deal with such a situation. The new development revealing the biofilm forming ability of Salmonella is a challenge to food scientists to go for steps that will have to ensure total destruction of this pathogen present in food both free as well as in biofilm format. Dry foods can no more be taken as free from Salmonella risk since this pathogen can contaminate, form biofilm and stay there till right conditions arrive for their proliferation. Biofilms can pass through the highly acidic environment of the stomach and "wake up" later in the intestine to bring havoc with the attendant consequences. With the discovery of biofilm phenomenon, food scientists are likey to come up with new techniques that can penetrate the biofilms and destroy the bacteria for making the food safer.  


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