![Metabolic reprogramming and ecosystem impact of protist- and/or phage-treated Synechococcus. <b>A</b> Uninfected cyanobacterium. <b>B</b> Cyanobacteria with protist. The presence of the protist modifies the abundance of certain exmetabolites. <b>VS</b> Cyanoviro cells only. Cyanophages reprogram P acquisition, photosynthesis, energy pathways and nucleotide metabolism towards building new phages. <b>D</b> Cyanoviro cells with protist. The energy (eg, ATP) and resource (eg, reducing power, phosphate, nucleotide, and amino acid) demand of phage infection is highest for cyanovirocells co-cultured with a protist. Cyanovirocells show the greatest changes in exometabolites, as shown by the release of nutrients, either by diffusion or active transport across the membrane (<b>VS</b>, <b>D</b>). This nutrient pool is available to the ecosystem, including uptake by protists (<b>D</b>). Credit: <i>Communications ISME</i> (2022). DOI: 10.1038/s43705-022-00169-6″ width=”800″ height=”530″/><figcaption class= Attack on 2 fronts leads ocean bacteria to require carbon boost](https://oponame.com/wp-content/uploads/2022/10/A-two-pronged-attack-may-force-ocean-bacteria-to-absorb-more.jpg)
The types of ocean bacteria known to absorb carbon dioxide from the air require more energy – in the form of carbon – and other resources when simultaneously infected by viruses and facing attacks from nearby predators. , according to new research.
Viruses are abundant in the ocean, and research now suggests that marine viruses have beneficial functions, including helping to drive absorbed carbon from the atmosphere to permanent storage at the ocean floor. When viruses infect other microbes in this environment (and anywhere, in fact), the interaction results in the creation of entirely new organisms called “virocells”.
In this new study, the researchers worked with cyanovirocells, cyanobacteria that take up carbon and release oxygen through photosynthesis and which have been infected with viruses. Analysis of changes in gene activation and metabolism of infected bacteria under laboratory conditions designed to mimic nature raises an intriguing possibility: the dual threat of viral infection and drift among hungry predatory microbes could lead cyanovirocells to absorb more carbon.
“More energy for these organisms probably means more CO2 fixation, so I suspect carbon sinking and carbon sequestration from the atmosphere is greater due to the interaction between predators, photosynthetic bacteria, and viruses,” said Cristina Howard-Varona, first author of the study and microbiology researcher at Ohio. State University.
The study was published online recently in the journal Communications ISME.
This work marks the first time that researchers have observed these bacteria as they are simultaneously infected with viruses and floating around in the presence of organisms, called protists, that eat them.
“The ocean covers 70% of our planet and protects us from climate change – and below the surface are all these complex interactions that we know so little about,” said study co-lead author Matthew Sullivan. and Professor of Microbiology at Ohio State.
“What we’ve learned is that these photosynthetic bacteria, which are the biggest contributor to climate change in the oceans, don’t just live their own lives. They’re attacked by larger organisms that eat them and much smaller ‘organisms’ – the viruses that infect them,” Sullivan said. understand how virocells contribute to marine cycles and affect climate change.”
The research team created ocean-like conditions by combining Synechococcus cyanobacteria, viruses and a protist called Oxyrrhis marina in seawater to create cyanovirocells which were then attacked by the predatory protist. They then compared the gene expression of the infected bacteria and the metabolic changes observed under these conditions with three controls: uninfected bacteria alone, cyanovirocells alone and uninfected bacteria in the presence of protists.
Using various computational techniques, the researchers observed significant differences in infected bacteria’s gene expression and metabolism-related molecules when the predatory protists were introduced to the marine environment – and noted that some of these changes were attributed to the infecting virus inside the cell, suggesting that the presence of the protist could be detected by the cyanovirocell.
“The entity that comes out of viral infection – the cyanovirocell – has a completely different metabolism and lifespan, and it cares about different functions,” Howard-Varona said. “And in the presence of the larger protist, those virocells require more resources and more energy to survive. You have to see all three players at the same time to see the increased energy demand.
“In this setting, the virus needs more energy to create more copies of itself, but where does it get it? It fixes carbon, which is converted into sugars, and the sugars are burned as of energy.”
The cyanovirocells also released metabolism-related nutrients into the water, which were eaten by the protists – observations that had never been made before.
Microbes in the ocean absorb half the human-generated carbon dioxide in the atmosphere and produce half the oxygen we breathe, but there is still much to learn about all the ecosystem factors at play in this. process.
“This work represents baseline data that is important for furthering our understanding of how the carbon cycle works in the oceans and the role that viruses play,” said Sullivan, also a professor of civil, environmental and geodetic engineering and founding director of the Ohio State’s Center. of microbiome science.
Viruses reprogram cells into different virocells
Cristina Howard-Varona et al, Impacts of protists on marine cyanovirocell metabolism, Communications ISME (2022). DOI: 10.1038/s43705-022-00169-6
Provided by Ohio State University
Quote: A two-pronged attack can force ocean bacteria to absorb more carbon (October 18, 2022) Retrieved October 18, 2022 from https://phys.org/news/2022-10-fronts-ocean-bacteria-carbon.html
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