Probiotic Escherichia coli strain Nissle 1917 outcompetes intestinalpathogens during biofilm formation

Many bacterial infections are associated with biofilm formation. Bacterialbiofilms can develop on essentially all kinds of surfaces, producing chronicand often intractable infections. Escherichia coli is an importantpathogen causing a wide range of gastrointestinal infections. E. coli strain Nissle 1917 has been used for many decades as a probiotic againsta variety of intestinal disorders and is probably the best field-tested E. coli strain in the world. Here we have investigated the biofilm-formingcapacity of Nissle 1917. We found that the strain was a good biofilm former.Not only was it significantly better at biofilm formation than enteropathogenic,enterotoxigenic and enterohaemorrhagic E. coli strains, it was alsoable to outcompete such strains during biofilm formation. The results supportthe notion of bacterial prophylaxis employing Nissle 1917 and may partiallyexplain why the strain has a beneficial effect on many intestinal disorders.