Dubbed Halomonas phage vB_HmeY_H4907, the new bacteria-infecting virus is the deepest isolated siphovirus from the ocean, and it represents a novel abundant viral family in the ocean.
Halomonas phage vB_HmeY_H4907. Scale bar – 100 nm. Image credit: Su et al., doi: 10.1128/spectrum.01912-23.
“To our best knowledge, this is the deepest known isolated phage in the global ocean,” said Dr. Min Wang, a marine virologist at the Ocean University of China.
“Our analysis of the viral genetic material points to existence of a previously unknown viral family in the deep ocean, as well as new insights into the diversity, evolution and genomic features of deep-sea phages and phage-host interactions.”
vB_HmeY_H4907 is a so-called bacteriophage, or a virus that infects and replicates inside bacteria.
It infects Halomonas meridiana, a Gram-negative gammaproteobacterium isolated from surface sediment from the Mariana Trench at a depth of 8,900 m (29,200 feet).
Halomonas bacteria are often found in sediments from the deep seas and from hydrothermal vents, geyser-like openings on the seafloor that release streams of heated water.
“Halomonas belong to the order Oceanospirillales and can be found in various habitats, including the Antarctic, Marianas Trench, and deep-sea hydrothermal vents,” the researchers said.
“They were also widely used in synthetic biology because members of Halomonas are well known for their capacity to break down petroleum hydrocarbons, flourish in environments with high salt concentrations and alkaline pH, and have a high tolerance to contamination.”
“They are also abundant in the Mariana Trench, suggesting that they may play an essential role in hadal environments.”
The genomic analysis of vB_HmeY_H4907 suggests that it is distributed widely in the ocean and has a similar structure to its host.
The new virus is evolutionarily distant from other reference viruses and forms a separate branch with unique conserved protein genes, representing a new family named Suviridae.
“The study points to new questions and research areas focused on the survival strategies of viruses in harsh, secluded environments — and how they co-evolve with their hosts,” Dr. Wang said.
“vB_HmeY_H4907 is lysogenic, which means it invades and replicates inside its host, but usually without killing the bacterial cell. As the cell divides, the viral genetic material is also copied and passed on.”
“In future studies, we plan to investigate the molecular machinery that drives interactions between deep-sea viruses and their hosts.”
“We’re also searching for other new viruses in extreme places, which would contribute to broadening our comprehension of the virosphere.”
“Extreme environments offer optimal prospects for unearthing novel viruses.”
A paper on the findings appears in the journal Microbiology Spectrum.
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Yue Su et al. Identification and genomic analysis of temperate Halomonas bacteriophage vB_HmeY_H4907 from the surface sediment of the Mariana Trench at a depth of 8,900 m. Microbiology Spectrum, published online September 20, 2023; doi: 10.1128/spectrum.01912-23
