, Volume 252, Issue 3, pp 199-201

Extracellular DNA in aquatic ecosystems may in part be due to phycovirus activity

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In a eutrophic lake, a crash of the algal population was followed by a significant increase in the number of virus-like particles (from ca. 1 106 ml−1 to ca. 26 106 ml−1), and soon thereafter by an increase of the amount of extracellular DNA (from ca. 20 µg l−1 to ca. 40 µg l−1). The same pattern of correlation between decrease of algae and increase of viruses and extracellular DNA could be demonstrated by an in vitro experiment with a Chlorella-virus-system. Lysis of algae by viruses increased both the number of viruses and the amount of DNA in the culture medium. Extracellular DNA mainly consisted of material with a molecular weight below 500 bp.

The Chlorella-virus-system is discussed. It could be used as a model-system for studying the dynamics of interaction of viruses and algae in aquatic ecosystems.