Effects of the Newly Isolated T4-like Phage on Transmission of Plasmid-Borne Antibiotic Resistance Genes via Generalized Transduction.

Junxuan Zhang,Xiaolu He,Junlin Liu,Qin Zhou,Shuqing Shen,Mengya Shi,Yongxue Sun,Mianzhi Wang

doi:10.3390/v13102070

Abstract

Bacteriophages are the most abundant biological entities on earth and may play an important role in the transmission of antibiotic resistance genes (ARG) from host bacteria. Although the specialized transduction mediated by the temperate phage targeting a specific insertion site is widely explored, the carrying characteristics of “transducing particles” for different ARG subtypes in the process of generalized transduction remains largely unclear. Here, we isolated a new T4-like lytic phage targeting transconjugant Escherichia coli C600 that contained plasmid pHNAH67 (KX246266) and encoded 11 different ARG subtypes. We found that phage AH67C600_Q9 can misload plasmid-borne ARGs and package host DNA randomly. Moreover, for any specific ARG subtype, the carrying frequency was negatively correlated with the multiplicity of infection (MOI). Further, whole genome sequencing (WGS) identified that only 0.338% (4/1183) of the contigs of an entire purified phage population contained ARG sequences; these were floR, sul2, aph(4)-Ia, and fosA. The low coverage indicated that long-read sequencing methods are needed to explore the mechanism of ARG transmission during generalized transduction.

Highlights

Bacterial viruses or bacteriophages are the most abundant biological entities on earth and can be divided into lytic or temperate phages, according to their lifestyles [1,2].Temperate phages integrate their DNA into the host genome and their lysogenic cycles enable vertical transmissions with the host DNA [3]
A lytic phage was isolated from a pig farm sewage treatment pond in Huizhou, China, named AH67C600_Q9, which was able to lyse E. coli AH67C600
Phage particles containing host DNA most likely would be incapable of producing another round of a productive infection

Summary

Introduction

Bacterial viruses or bacteriophages (phages) are the most abundant biological entities on earth and can be divided into lytic or temperate phages, according to their lifestyles [1,2] Temperate phages integrate their DNA into the host genome and their lysogenic cycles enable vertical transmissions with the host DNA [3]. Activation of lysogenized prophage occurs under specific physical or chemical stressors, such as ultraviolet light or via intrastrand crosslinking with drugs, such as mitomycin C, and will induce the prophage to enter a lytic cycle This process can result in incorporation of host DNA due to inaccurate cutting so that HGT events with antibiotic resistance genes (ARG) can occur in the infection cycle by homologous recombination

Methods

Results

Discussion

Conclusion