Noteworthy
Absorbed in our daily activities and concerns, personal, local or global, we remain largely unaware of how life unfolds on this planet. Viruses, and especially those in our vast oceans, play a major life-defining role.
Viruses are considered the most abundant forms of "life" on our planet. Our oceans, which cover more than 70% of the Earth's surface, are teeming with an estimated 1030 viral particles. These viruses need to infect cells to produce progeny particles, which they do by hijacking the host metabolic machinery. This translates into millions of infections every second, an ongoing process that sabotages the lifestyle of a host organism. Viruses are well known for causing cell death and disease. They also transfer genetic information that drives evolution. But it is the overwhelming number of viruses and their interactions that shock us into realizing the harsh reality of what it means to live under the constant threat of predation.
In the oceans, most of the living biomass is made of microbes, which are fundamental for cycling of nutrients and energy. Among these are plentiful bacteria that are susceptible to viral attack by bacteria-loving viruses: bacteriophages. But not all bacteriophages behave the same way. In addition to lytic and lysogenic phages, some phages produce chronic infections that allow them to persist within a host cell without killing it by releasing progeny phage particles via extrusion or budding.
A recent study by Wang and collaborators probes into the mysteries of phage-bacteria interactions by studying the growth behavior of two difficult-to-cultivate deep see bacterial Lentisphaerae strains. By following up on an observation that polysaccharide supplementation promoted bacterial growth, they discovered that polysaccharides induce the release of bacteriophages. They use diverse approaches to show that these strains harbor chronic bacteriophages that release particles without lysing the host cell. The authors also hypothesize that these bacteriophages, which encode proteins associated with polysaccharide transport and degradation, probably assist the host cell to metabolize polysaccharides. In doing so, they help bacteria grow and proliferate, generating more hosts for their own reproduction. (See the paper for figure explanation.)
Exploring deep sea microbial life is a challenge. Despite this, the authors' careful analyses of recently cultivated bacteria provided insight into the impact of virus-bacteria interactions in marine ecosystems.
("Noteworthy" is the new format for STC's Thursday posts. Please read our Jan 20, 2025 post outlining this and other changes in our blog.)
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