Surface plasma induced elimination of antibiotic-resistant Escherichia coli and resistance genes: Antibiotic resistance, horizontal gene transfer, and mechanisms

Abstract

• Simultaneous elimination of ARB and ARGs is studied by surface plasma oxidation. • ARB and ARGs removal efficiency under various different conditions is assessed. • Horizontal gene transfer of ARGs during the plasma treatment was evaluated. • Contributions of active substances to ARB and ARGs elimination are identified. • Possible elimination mechanisms of ARB and ARGs are proposed. Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), as emerging environmental pollutants, are commonly detected in waters. Surface plasma was developed to simultaneously inactivate antibiotic resistant Escherichia coli (AR E. coli ) and remove its associated ARGs in water. 7.0 log AR E. coli was inactivated after 10 min surface plasma treatment; minimal inhibitory concentration (MIC) representing antibiotic resistance profiles decreased by 96.9%, 96.9%, and 98.4% for the tested tetracycline, amoxicillin, and gentamicin, respectively. The ARGs ( TetC , TetW , bla TEM -1 , and aac ( 3 ) -II ) and integron gene ( intI1 , indicator of horizontal gene transfer) also decreased by 1.04, 0.61, 1.84, 2.2, and 2.3 log copies within 10 min, respectively. Oxidizing substances in the surface plasma including OH, 1 O 2 , H 2 O 2 , O 3 , NO 2 − , and NO 3 − contributed to AR E. coli inactivation, resulting in membrane damage, biological process disruption, protein structure changes, and DNA damage. As a result, horizontal gene transfer of ARGs was inhibited by 63% after plasma treatment. Overall, surface plasma could be an effective technique to control ARB and ARGs in water.