S. sobrinus is a rare bacteria, as it is not present in all humans, and has been difficult for Jensen to work with. With working with the S. mutan strains they were able to get to the elusive S. sobrinus. Jensen states "Although it is rare, S. sobrinus produces acid more quicklu and is associated with the poorest clinical outcomes, especially among children, if S. sobrinus is present along with S. mutans, you're at risk for rampant tooth decay, which means there's some level of communication or synergy between the two that we don't understand yet."
This squencing has paved the road to a better understanding of the interactions between these two strains and how they create a devastating combo. What is known so far from Jensen is that " S. mutans bacteria sends out feelers in the form of a peptide to find out how many other S. mutans cells are nearby." the moment that there are enough they go on the offensive and begin to harm a persons mouth. This creates an imbalance of "good' bacteria to "bad" bacteria.
1 - https://bioengineering.illinois.edu/news/article/27184