Towards A Genetic Basis for Antibiotic Resistance in Chromobacterium Violaceum

The emergence of mutations in the genome is one of the major factors underlying evolution. Mutation as the cause of antibiotic resistance was studied in Chromobacterium violaceum for the antibiotics chloramphenicol and streptomycin. The wild-type C. violaceum was tested to be susceptible to low concentrations of both antibiotics (Chloramphenicol: MIC 8ug) (Streptomycin: MIC 10ug). Continuous exposure to the antibiotics at concentrations slightly lower than the MIC, resulted in resistance to the antibiotics.  This adaptive evolutionary phenomenon allowed growth on agar plates at high antibiotic concentrations (MIC: 200ug). The growth rates of these evolved strains 2-30 fold higher at varying concentrations of antibiotic. All genetic changes were delineated during the evolution of antibiotic resistance using next generation sequencing (Ion Torrent^TM). This talk will focus on the results of NGS and the functional impact of the genetic variations detected including AcrAB drug efflux pumps and ribosomal proteins like rpsL.