Eating Feta cheese made from raw milk in small seaside tavernas when you are on holiday in Greece could be a good way to combat food poisoning, according to researchers speaking today (Thursday 3 April 2008) at the Society for General Microbiology's 162nd meeting being held this week at the Edinburgh International Conference Centre.
“We were able to isolate lactic acid bacteria found in raw sheep milk from small farms in Macedonia, northern Greece. Several of these friendly bacteria naturally produce antibiotics that killed off dangerous food-poisoning bacteria like Listeria,” says Panagiotis Chanos, a researcher from the University of Lincoln. “Interestingly, we identified these friendly bacteria as enterococci, more commonly recognised as virulent and/or antibiotic resistant bacteria in hospitals. We found some strains could produce up to three different natural substances to fight different food pathogens.”
The unique taste of many local cheeses, especially from Greece and other parts of the Mediterranean, is mainly due to the enterococcal bacteria they contain. Apart from their sometimes sinister role when antibiotic resistant strains cause hospital infections, enterococci are important in the food flavouring and manufacturing industries.
Listeria is one of the most dangerous food poisoning bacteria because it can survive in places and conditions that other bacteria cannot. It can be found in foods made from animal products as a result of poor heat processing or mishandling, which causes post-production contamination, for example when butchers or retailers fail to wash their hands between touching cooked pies and raw meats.
“We hope that this work will lead to ways of fighting foodborne pathogens, using the naturally produced compounds called bacteriocins made by other bacteria,” says Mr Chanos. “We discovered that all the useful strains of bacteria that produced bacteriocins were able to grow in extreme conditions resembling those commonly found in foods, including the low temperatures found in our refrigerators and the salty conditions found in some cheese.”