AME 71:203-209 (2014)  -  DOI: https://doi.org/10.3354/ame01672

Flow cytometric enumeration of marine viral populations at low abundances

K. D. A. Mojica1,*, C. Evans1,3, C. P. D. Brussaard1,2

1Department of Biological Oceanography, NIOZ–Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands
2Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, 1090 GE Amsterdam, The Netherlands
3Present address: National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK
*Corresponding author:

ABSTRACT: Flow cytometric enumeration has advanced our ability to analyze aquatic virus samples and thereby our understanding of the ecological role viruses play in the oceans. However, low virus abundances are underestimated using the current flow cytometry (FCM) protocol. Our results revealed that low dilutions (<30-fold) not only decreased the total virus count but also limited the ability to differentiate between virus clusters. Here we report a simple and efficient method optimization for improving virus counts and optical resolution at low abundances. Raising the pH of the Tris-EDTA (TE) buffer to 8.2 successfully countered the effect of insufficient buffering capacity at low dilutions, which is caused by the higher proportion of acidic glutaraldehyde fixative in the final sample. The higher buffer pH did not interfere with virus counts at higher dilutions. We therefore recommend amendment of the standard FCM aquatic virus enumeration protocol using a TE buffer with pH 8.2 as a simple and efficient improvement.


KEY WORDS: Flow cytometry · Low abundance · Virus enumeration


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Cite this article as: Mojica KDA, Evans C, Brussaard CPD (2014) Flow cytometric enumeration of marine viral populations at low abundances. Aquat Microb Ecol 71:203-209. https://doi.org/10.3354/ame01672

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