Effects of CO2 on the transformation of antibiotic resistance genes via increasing cell membrane channels

Abstract

The increase of CO2 concentration in the atmosphere, water and soil environment can lead to the changes in microbial activities. However, the transformation of antibiotic resistance genes has not been investigated in the presence of higher levels of CO2. This study demonstrated that CO2 facilitated the transformation of pUC19 plasmid, carrying ampicillin resistance genes, into Escherichia coli. Mechanism studies revealed that the type Ⅱ secretion system, type Ⅳ pilus and some other secretion systems were enhanced by CO2, leading to DNA capture by pilus, larger cell pore sizes and more cell membrane channels. CO2 also increased reactive oxygen species production, leading to SOS response and cell membrane damage. Besides, changes in intracellular Fe2+ and Mg2+ concentrations induced by CO2 caused greater damage to the cell membrane and enhanced secretion systems, respectively. Overall, increased CO2 provided more cell membrane channels for plasmid uptake and led to higher transformation efficiencies. The potential risk of a natural factor on the transformation of ARGs was first studied in this study, which helps us understand the fate of ARGs in ecosystems. As the carbon emission will continue to grow and enhance the enrichment of CO2 in water and soil, the findings revealed a more severe public health issue under the background of carbon emission and CO2 leakage.