Laboratory evolution of S. aureus against a dehydroabietic acid derivative

In order to attempt to further elucidate the mechanism of action of a dehydroabietic acid (DHA) derivative, GHA36, a laboratory evolution experiment was performed in S. aureus UAMS-1 strain and the resulting cultures were sequenced and compared. 3 Lineages of UAMS-1 were exposed to GHA36 by doing sequential MIC's for 20 days. Every day, 5 µL of the bacterial suspension from the well with GHA36 concentration of 0.5x MIC were used to inoculate the next microtiter plate, resulting in 16 fold increase in MIC of all three lineages. DNA was extracted and sequenced for the starting UAMS-1 strain and the 3 lineages after 10 and 20 passages. Mutations in the tarB gene and genes related to purine biosynthesis are possibly related to the development of resistance to GHA36.