Isolation and Bacteriocin-Related Typing of .

subspecies is explored as an anti-cariogenic probiotic. Here, subjecting freshly stimulated saliva samples of 35 healthy volunteers, six epidemiologically unrelated and two related strains were isolated (prevalence around 20%) applying a newly developed three-step procedure. Furthermore, the probiotic strain 7746 (AB-Dentisanium®) was tested under a variety of environmental conditions for its inhibitory effect on six , two , 15 other oral or intestinal streptococci, 15 strains, and six representatives of other species including periodontopathogens. All except one of the strains were inhibited by 7746 colonies or culture supernatant concentrate but only if either the test cell number was low or the producer or its bacteriocin concentration, respectively, was high. OMI 332, OMI 315, OMI 335, OMI 238, and the intestinal OMI 339 were not inhibited, while the other 10 streptococcal strains (especially OMI 334 and intestinal OMI 326) showed a certain degree of inhibition. From the panel of other bacterial species only was slightly inhibited. With the exception of OMI 285 and OMI 291 that possessed a 7746 bacteriocin-like gene cluster, all strains and especially type strain 7747 were strongly inhibited by 7746. In conclusion, probiotic strain 7746 might antagonize the initiation and progression of dental caries by reducing if not too abundant. strains inhibit each other, but strains with similar bacteriocin-related gene clusters, including immunity genes, are able to co-exist due to cross-resistance. In addition, development of resistance and adaptation to 7746-bacteriocins was observed during our study and needs attention. Hence, mechanisms underlying such processes need to be further investigated using omics-approaches. On the manufacturing level, probiotic strains should be continuously tested for function. Further clinical studies investigating inhibition of by AB-Dentisanium® are required that should also monitor the impact on the oral microbiome composition including resident strains.