Abstract
AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 27:103-110 (2002) - doi:10.3354/ame027103 Reconsidering transmission electron microscopy based estimates of viral infection of bacterio- plankton using conversion factors derived from natural communities Markus G. Weinbauer1,*, Christian Winter2, Manfred G. Höfle1 1GBF - German Research Centre for Biotechnology, Department of Environmental Microbiology, Mascheroder Weg 1, 38124 Braunschweig, Germany 2Netherlands Institute for Sea Research (NIOZ), Department of Biological Oceanography, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands *Present address: Laboratoire d¹Océanographie de Villefranche (LOV), PB 28, 06234 Villefranche, France. E-mail: wein@obs-vlfr.fr ABSTRACT: The frequency of virus infected bacterial cells (FIC) was estimated in surface waters of the Mediterranean Sea, the Baltic Sea and the North Sea using the frequency of visibly infected cells (FVIC) as determined by transmission electron microscopy (TEM) and published average conversion factors (average 5.42, range 3.7 to 7.14) to relate FVIC to FIC. A virus dilution approach was used to obtain an independent estimation of FIC in bacterioplankton, and we provide evidence for the reliability of this approach. Across all investigated environments, FIC ranged from 2.4 to 43.4%. FIC data using both approaches were well correlated; however, the values were higher using the virus dilution approach. This indicates that the TEM approach has the potential to reveal spatiotemporal trends of viral infection; however, it may underestimate the significance of viral infection of bacteria when average conversion factors are used. Using data from the virus dilution approach and the TEM approach, we calculated new conversion factors for relating FVIC to FIC (average 7.11, range 4.34 to 10.78). Virally caused mortality of bacteria estimated from published FVIC data of marine and freshwater systems and using the new conversion factors ranged from not detectable to 129%, thus confirming that viral infection is a significant and spatiotemporally variable cause of bacterial cell death. KEY WORDS: Phage · Virus · Mortality · Lysogeny · Latent period Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 27, No. 2. Online publication date: March 15, 2002 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2002 Inter-Research.
Highlights
The incorporation of the role of viruses into the microbial food web has refined our understanding of the ecological and biogeochemical role of microorganisms in aquatic systems (Fuhrman 1999, Wilhelm & Suttle 1999, Wommack & Colwell 2000)
A virus dilution approach was used to obtain an independent estimation of frequency of virus infected bacterial cells (FIC) in bacterioplankton, and we provide evidence for the reliability of this approach
FIC data using both approaches were well correlated; the values were higher using the virus dilution approach. This indicates that the transmission electron microscopy (TEM) approach has the potential to reveal spatiotemporal trends of viral infection; it may underestimate the significance of viral infection of bacteria when average conversion factors are used
Summary
The incorporation of the role of viruses into the microbial food web has refined our understanding of the ecological and biogeochemical role of microorganisms in aquatic systems (Fuhrman 1999, Wilhelm & Suttle 1999, Wommack & Colwell 2000). One of the very first reports suggesting that viruses are significant players in microbial food webs estimated that up to 7% of the bacteria in marine systems contained mature virus particles corresponding to up to 70% infected bacteria (Proctor & Fuhrman 1990) These data were based on the assumption that mature phage particles are only visibly during the last 10% of the latent period. Later these authors performed an electron microscopy study with isolated phage-host systems to obtain more reliable conversion factors (average 5.42, range 3.7 to 7.14) for relating FVIC to the frequency of virus infected bacterial cells (FIC) (Proctor et al 1993). We used these conversion factors to reevaluate published data on FVIC, FIC and VMB from bacterioplankton
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