Abstract
Viruses are far more abundant than cellular microorganisms in the marine ecosystem. However, very few viruses have so far been isolated from marine sediments, especially hydrothermal vent sediments, hindering the understanding of the biology and ecological functions of these tiny organisms. Here, we report the isolation and characterization of a temperate bacteriophage, named PVJ1, which infects Psychrobacillus from a hydrothermal vent field in Okinawa Trough. PVJ1 belongs to the Myoviridae family of the order Caudovirales. The tailed phage possesses a 53,187 bp linear dsDNA genome, with 84 ORFs encoding structural proteins, genome replication, host lysis, etc. in a modular pattern. The phage genome is integrated into the host chromosome near the 3′-end of deoD, a gene encoding purine nucleoside phosphorylase (PNP). The phage integration does not appear to disrupt the function of PNP. The phage DNA is packaged by the headful mechanism. Release of PVJ1 from the host cell was drastically enhanced by treatment with mitomycin C. Phages encoding an MCP sharing significant similarity (≥70% identical amino acids) with that of PVJ1 are widespread in diverse environments, including marine and freshwater sediments, soils, artificial ecosystems, and animal intestines, and primarily infect Firmicutes. These results are valuable to the understanding of the lifestyle and host interactions of bacterial viruses at the bottom of the ocean.
Highlights
Viruses are the most abundant biological entities in the ocean, and those in marine sediments are especially abundant and extraordinarily diverse [1,2,3,4]
Metagenomic analysis shows that viruses in hydrothermal vents are predominantly lysogenic and carry auxiliary metabolic genes that function to regulate the physiological activities of the host [14]
For qPCR quantification, 10 μL phage suspension was added into 500 μL bacterial cultures at exponential growth phase, Mitomycin C was added after culturing to the stationary phase, and the total Psychrobacillus virus J1 (PVJ1) DNA before and after induction was quantified by qPCR
Summary
Viruses are the most abundant biological entities in the ocean, and those in marine sediments are especially abundant and extraordinarily diverse [1,2,3,4]. Four of them infect Bacillus or Geobacillus, and they are all lytic [8,9,10,11] These phages possess head-tailed morphotypes similar to those of the majority of phages isolated from terrestrial hot springs [12]. Metagenomic analysis shows that viruses in hydrothermal vents are predominantly lysogenic and carry auxiliary metabolic genes that function to regulate the physiological activities of the host [14]. We report the isolation and characterization of PVJ1, a bacteriophage that infects a mesophilic Psychrobacillus strain, from a sediment sample taken from a hydrothermal vent field in Okinawa Trough. PVJ1 is a temperate phage of the Myoviridae family of the order Caudovirales, and capable of integrating its 53,187 bp linear dsDNA genome into the host genome at a unique site within a gene encoding purine nucleoside phosphatase. Phages encoding a MCP sharing significant similarity (≥70% identical amino acids) with that of PVJ1 infected Firmicutes and are widespread in aquatic environments, soils, and animal intestines
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