RESEARCH

Full list of author information is available at the end of the articleBackground The immunomodulatory potential of probiotic bacteria is of increasing interest for prophylactic and therapeutic options in various complex disorders, ranging from diar-rhea to allergy. However, clinical and intervention stu-dies with probiotics are not universally effective. For instance, the well-known probiotic Lactobacillus rham-nosus GG (LGG) shows promising results in the preven-tion of atopic disease [1-3], prevention and relief of diarrhea [4] and prevention of respiratory tract infec-tions in children [5], while the results in Crohn’s disease are less promising [6-8]. Clearly, the mode and timing of delivery and severity of the conditions are important fac-tors in determining probiotic efficacy. To select the opti-mal strain for each application, detailed molecular knowledge would be of great help. Many immunomodu