microbial abundance ~10^6 microbes/ml: viral abundance ~10^7 viruses/ml
||Wigington CH et al., Re-examination of the relationship between
marine virus and microbial cell abundance. Nature Microbiology, 25 January 2016 article number: 15024 DOI: 10.1038/NMICROBIOL.2015.24 p.1 right column top paragraph
|| Wommack, K. E. & Colwell, R. R. Virioplankton: viruses in aquatic ecosystems. Microbiol. Mol. Biol. Rev. 64, 69–114 (2000).  Weinbauer, M. G. Ecology of prokaryotic viruses. FEMS Microbiol. Rev. 28, 127–181 (2004).PubMed ID10704475, 15109783
||P.1 left column bottom paragraph: "Observations accumulated over the past 25 years have noted a wide variation in the VMR [‘virus-to-microbial cell ratio’], yet there is a consensus that a suitable first approximation is that the VMR is equal to 10 (Supplementary Table 1 BNID 112654). This ratio also reflects a consensus that typical microbial abundances are approximately 10^6 per ml and typical virus abundances are approximately 10^7 per ml [primary sources]. Yet, the use of a fixed ratio carries with it another assumption—that of linearity—that is, if microbial abundance were to double, then viruses are expected to double as well. An alternative is that the relationship between virus and microbial abundances is better described in terms of a nonlinear relationship, for example, a power law."