The Role of Marine Viruses and the Understanding of Nutrient Cycling

A review of: Brussaard, C.P.D., Wilhelm, S.W., Thingstad, F., Weinbauer, M.G., Bratbak, G., Heldal, M., Kimmance, S.A., Middelboe, M., Nagasaki, K., Paul, J.H., Schroeder, D.C., Suttle, C.A., Vaque, D., Wommack, K.E., (2008), Global-scale processes with a nanoscale drive: the role of marine viruses, The ISME Journal, 2, 575-578

Viruses represent the largest pool of genetic diversity and are by far the most numerous of all biotic agents on earth, with an estimated number of around 10^30 viruses in the ocean, they can take over cells in organisms varying from bacteria to sharks, to humans. However, even given this data, the extent of viruses in nanoscale processes are rarely linked to global scale biodiversity and biogeochemistry.

The poor connections between viruses and biogeochemistry is mostly due to the processes being ignored in most carbon flux models. Although much of this data is as of yet unknown, there is much room for research into completing comprehensive models including it. However, due to the findings that they accelerate the recycling of growth limiting nutrient elements in the photic zone, should they be measured as a hinderance or a stimulant to the primary production. There is much ongoing debate as to whether viruses short circuit the biological pump by releasing elements back to their dissolved phase, whether they prime the biological pump by accelerating host export from the euphotic zone, or whether they drive particle aggregation and transfer of carbon into the deep sea. They have also been hypothesized to contribute to the resilience of ecosystems.

An area where viruses are moving forward in biogeochemistry is the combination of molecular techniques such as molecular probes and viral gene expression, to allow for biodiversity, biogeochemistry and genomics to come together. With recent developments allowing for the wealth of the information of the viral genetic reservoir to be discovered using genomic tools. Although, while viruses can be key parts of biogeochemical cycles, it is in what way they do this that is an important area for study. Without the deciphering of metaviromes being required for testing, the ‘blueprints’ of the viruses actions are still locked in the viroplankton metagenomic data sets. Resulting in many viruses that are not in the genomic database having unknown functions. This would be greatly helped with a smooth communication between studies of the virus-host systems in marine microbes and viral biogeochemistry.

In future, the role of viruses can be further understood with tests such as the quantitative reverse transcription–PCR, allowing the accurate measurement of messenger RNA and the expression of the genes. Virology, especially in aquatic and marine habitats, will allow for future collection and understanding of data on the links between the virus-host systems and nutrient cycling and energy flow. With the study of a subject that is still highly debated as to whether it is a life-form in itself, is always going to be a difficult challenge, but backed up with current knowledge, there is the potential to expand our knowledge of viruses and their role in the marine environment in future to give us a greater understanding of how the worlds most important systems work.