Photocatalysis\nInhibits the Emergence of Multidrug-Resistant\nBacteria in an Antibiotic-Resistant Bacterial Community in Aquatic\nEnvironments

Bacterial\nantibiotic resistance has recently attracted increasing\namounts of attention. Here, an artificially antibiotic-resistant bacterial\ncommunity (ARBC) combined with five different constructed antibiotic-resistant\nbacteria (ARB) with single antibiotic resistance, namely, kanamycin\n(KAN), tetracycline (TET), cefotaxime (CTX), polymyxin B (PB), or\ngentamicin (GEM), was studied for the stress response to photocatalysis.\nWith photocatalytic inactivation, the transfer and diffusion of antibiotic\nresistance genes (ARGs) in the ARBC decreased, and fewer multidrug-resistant\nbacteria (MDRB) emerged in aquatic environments. After several days\nof photocatalytic inactivation or Luria broth cultivation, >90%\nARB\nwere transformed to antibiotic-susceptible bacteria by discarding\nARGs. Bacteria with double antibiotic resistance were the dominant\nspecies (99%) of residual ARB. The changes in ARG abundance varied,\ndecreasing for the GEM and TET resistance genes and increasing for\nthe KAN resistance genes. The change in the antibiotic resistance\nlevel was consistent with the change in ARG abundance. Correspondingly,\npoint mutations occurred for the KAN, CTX and PB resistance genes\nafter photocatalytic inactivation, which might be the reason why these\ngenes persisted longer in the studied ARBC. In summary, photocatalytic\ninactivation could reduce the abundance of some ARGs and inhibit the\nemergence of MDRB as well as block ARG transfer in the bacterial community\nin aquatic environments. This work highlights the advantages of long-term\nphotocatalytic inactivation for controlling antibiotic resistance\nand facilitates a better understanding of bacterial communities in\nreal aquatic environments.