Distribution of Antibiotic Resistance Genes within Viral Metagenomes of Urban Wastewater Treatment Plants

초록

Bacteriophages (phages), viruses that infect bacteria, are found in diverse environments including soil, river, wastewater, and guts. As phages infect their hosts, they may randomly acquire a piece of their host genomes, leading to spread of the gene to another host or to its progeny. One of the well-known bacterial genes that are carried by phages is antibiotic resistance genes (ARGs). Gut microbiomes, which are often exposed to diverse antibiotics and have developed ARGs, are commonly released to environment through wastewater treatment plant (WWTP) effluents, along with their phages. This study focuses on the analyses of viral metagenomes (viromes) generated from 4 WWTPs in Seoul and Gwangju of South Korea to observe the distribution of ARGs within phage genomes. For all 4 WWTP viromes, viral fractions of the raw sewage contained the highest ratio of ARGs, which comprised up to 0.48% of virome reads while less than 0.05% of the virome reads of neighboring surface waters were predicted to be ARGs. The most commonly found ARG within the viromes were β-lactamases and multidrug efflux pumps. Interestingly, types of β-lactamases found in two cities differed that in Seoul, class C β-lactamases were dominant while those of class A and B showed dominance in Gwangju. Collectively, the phages must be considered as significant vehicles of ARGs, especially of β-lactamases. [Supported by the Korean Ministry of Environment as “the Environmental Health Action Program” (201600135004)]