Conjugation transfer of plasma-induced sublethal antibiotic resistance genes under photoreactivation: Alleviation mechanism of intercellular contact

Dissemination of antibiotic resistance genes (ARGs) is a huge challenge worldwide. Information regarding underlying mechanisms of conjugation transfer of sublethal ARGs under photoreactivation is still lacking. In this study, experimental exploration and model prediction were conducted to evaluate the effects of photoreactivation on conjugation transfer of plasma-induced sublethal ARGs. The experimental results showed that reactive species (O2-•, 1O2, and •OH) generated in the plasma process led to 0.32, 1.45, 3.21, 4.10, and 3.96-log removal for tetC, tetW, blaTEM-1, aac(3)-II, and intI1 after 8 min treatment at 18 kV, respectively. Their attacks led to breakage and mineralization of ARGs-containing DNA and disturbance of bacterial metabolism. The conjugation transfer frequency increased by 0.58-fold after 48 h of photoreactivation compared with the plasma treatment, as well as the abundances of ARGs and reactive oxygen species levels. The alleviation effects of photoreactivation were independent of cell membrane permeability, but related to promotion of intercellular contact. Ordinary differential equation model predicted that the stabilization time of long-term transfer of ARGs significantly increased by 50 % after photoreactivation compared with the plasma treatment, and the conjugation transfer frequency also increased. This study firstly revealed the mechanisms of conjugation transfer of sublethal ARGs under photoreactivation.