Reduced research time (RRT) is a bonus that can be obtained from Evolved Bacteria. It decreases the time that it takes to complete all activities in the Research Labs with the exception of sending and recalling Scientists in the Planetary Research section.
The RRT bonuses from different Evolved Bacteria are not additive. Instead, each Evolved Bacteria with the bonus reduces the research time remaining instead of the original research time. [1]
For example, if the player has three Evolved Bacteria equipped with RRT of 13.3%, 12.1%, 13.8%, then the total RRT would be 34.3% not 39.2%. [1]