Eternal sandwiches - or the end of MRSA?



Many newspapers this week reported the discovery of bisin, a naturally occurring lantibiotic that was discovered by a microbiologist at the University of Minnesota. Bisin has a wide range of antimicrobial effectiveness, and could even be used as a food preservative that would make sandwiches, dairy food, eggs, ready meals, canned meat and other substances safe to eat for years after their production.


Bisin is similar to another bactericide, nisin, which is already used to preserve processed meats and cheese. Their similarities are sufficient for bisin to be recognised as safe to use in food, without requiring pharmacological testing. Nisin is widely for its inhibitory effects against most Gram-positive bacteria. However, bisin offers new advantages of both bactericidal and inhibitory effects against Gram-negative bacteria, such as E. coli and Salmonella, as well as against Gram-positive bacteria. Bisin could therefore be used as a natural additive, in place of artificial chemical preservatives, which often have unwanted side-effects or are perceived to reduce the nutritional value of food.

By extending the shelf-life of food products, bisin could help to reduce food wastage, as well as provide more transportable and long-life food for famine-hit countries - but its discovery has also raised some questions.

Firstly, would a bisin-preserved sandwich have the same nutritional value, texture and taste, one year after being manufactured? And is fresh food that has been artificially preserved a good thing? When it was demonstrated last year that burgers supplied by a well-known international chain of fast-food restaurants don't appear to decompose, even months after production, the media and general public reacted with horror.

Secondly, if bisin were to become the preservative of choice to combat both Gram-negative and -positive bacteria, could its ubiquitous use lead to the development of bacterial resistance to bisin?

A further use for bisin has been proposed as a probiotic or dietary supplement - but what long-term effects might this have on the normal populations of bacteria in human intestines?

Perhaps these questions can't be answered just yet. More importantly, there are other highly appealing benefits to bisin that far exceed the advantages of extending food use-by dates.

Bisin can prevent the growth of E. coli and Salmonella in food, therefore bisin has the potential to wipe out the threat of food-borne illnesses, which are reportedly responsible for one in six illnesses in the USA per year, costing $152 bn, causing hundreds of thousands of hospitalisations and 3,000 deaths annually. Salmonella alone causes 28 per cent of these deaths, according to a report by the Center for Disease Control. Simply adding bisin, a natural and safe additive, could dramatically reduce food-borne ill health and all its associated costs.

Another vitally important potential use of bisin could be an alternative to current antibiotics, for treating bacterial infections. If bisin's powerful effects are such that bacteria cannot easily develop resistance to bisin, it could transform current healthcare by overcoming the problem of MRSA (meticillin-resistant Staphylococcus aureus). This so-called superbug with increasing resistance to antibiotics is responsible for increasing numbers of hospitalisations, particularly among children, and billions of dollars in healthcare and MRSA management costs.

Leaving aside the scaremongering about eternal sandwiches, bisin sounds too good to be true. Bring it on!


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