The origin of the bacterial strains in ProBiora can be found in the studies linked below:
The Hillman 1985 paper Hillman paper describes the isolation of Streptococcus sanguis KJ3 (what we now know as Streptococcus oralis KJ3) and Streptococcus uberis KJ2.
The S. rattus paper S Rattus paper describes the isolation of Streptococcus rattus JH145, a naturally occurring variant of S. mutants that does not produce lactic acid (which is a major contributor to tooth decay).