Nano-Al₂O₃ can mediate transduction-like transformation of antibiotic resistance genes in water

The prevalence of various antibiotic resistance genes (ARGs) and resistant bacteria has caused global public health risks. The carrier transport mediated by phages or membrane vesicles is an important way for horizontal transfer of ARGs. Nano metal oxide particles (NMOPs), which can enter cell through the cell membrane, may be used as the carriers of genes. However, whether they can be used as transmembrane delivery vectors for the horizontal ARG transfer remains unknown. Here, we set up a model of MONPs-mediated transfer of ARGs, and demonstrate that NMOPs, especially for nano-Al₂O₃, can act as carriers mediating the transduction-like ARG transformation in water. The highest transfer rate mediated by nano-Al₂O₃ is 4.53 × 10⁴ cfu/mmol, and it is 10⁴ times higher than that of control. Nano-Al₂O₃ can combine with plasmid coding for ARGs to form high-density package and prevent ARGs from degradation by endonuclease. The results of superresolution fluorescence microscopy and transmission electron microscopy show that nano-Al₂O₃ can carry ARGs for transmembrane transport. Genome-wide transcription microarray and qPCR indicate that SOS response was closely related to transduction-like ARG transformation mediated by nano-Al₂O₃. This study is the first to demonstrate that as a new transmembrane carrier, nano-Al₂O₃ can also cause ARGs diffusion in water.