Enumeration and biomass estimation of planktonic bacteria and viruses by transmission electron microscopy

Børsheim, Knut Yngve; Bratbak, Gunnar; Heldal, Mikal

doi:10.1128/aem.56.2.352-356.1990

Cited by 276 publications

(91 citation statements)

References 31 publications

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“…Head size distribution of viruses can vary with time and space [106,[159][160][161][162][163], however, not all of the studies have shown such changes [86,94,95,101]. Heterotrophic nanoflagellates are a major type of predators of prokaryotes in aquatic systems and their grazing is sizeselective, i.e., they graze preferentially on a particular size class [164,165].…”

Section: Morphological and Size Characteristicsmentioning

confidence: 99%

Ecology of prokaryotic viruses

2004

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The finding that total viral abundance is higher than total prokaryotic abundance and that a significant fraction of the prokaryotic community is infected with phages in aquatic systems has stimulated research on the ecology of prokaryotic viruses and their role in ecosystems. This review treats the ecology of prokaryotic viruses ('phages') in marine, freshwater and soil systems from a 'virus point of view'. The abundance of viruses varies strongly in different environments and is related to bacterial abundance or activity suggesting that the majority of the viruses found in the environment are typically phages. Data on phage diversity are sparse but indicate that phages are extremely diverse in natural systems. Lytic phages are predators of prokaryotes, whereas lysogenic and chronic infections represent a parasitic interaction. Some forms of lysogeny might be described best as mutualism. The little existing ecological data on phage populations indicate a large variety of environmental niches and survival strategies. The host cell is the main resource for phages and the resource quality, i.e., the metabolic state of the host cell, is a critical factor in all steps of the phage life cycle. Virus-induced mortality of prokaryotes varies strongly on a temporal and spatial scale and shows that phages can be important predators of bacterioplankton. This mortality and the release of cell lysis products into the environment can strongly influence microbial food web processes and biogeochemical cycles. Phages can also affect host diversity, e.g., by 'killing the winner' and keeping in check competitively dominant species or populations. Moreover, they mediate gene transfer between prokaryotes, but this remains largely unknown in the environment. Genomics or proteomics are providing us now with powerful tools in phage ecology, but final testing will have to be performed in the environment.

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Section: Morphological and Size Characteristicsmentioning

confidence: 99%

Ecology of prokaryotic viruses

2004

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“…Transmission electron microscopy (TEM) is the most direct method for counting viral particles and can be Food Environ Virol (2015) 7:96-111 105 successfully used for determining the concentration of MS2 phage-like particles (Borsheim et al 1990). However, the long analysis time required, as well as the high cost and difficulty of this method has led to the development of alternative methods.…”

Section: Quantification Of Ms2 Phage-like Particlesmentioning

confidence: 99%

Methods for Preparation of MS2 Phage-Like Particles and Their Utilization as Process Control Viruses in RT-PCR and qRT-PCR Detection of RNA Viruses From Food Matrices and Clinical Specimens

2015

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RNA viruses are pathogenic agents of many serious infectious diseases affecting humans and animals. The detection of pathogenic RNA viruses is based on modern molecular methods, of which the most widely used methods are the reverse transcription polymerase chain reaction (RT-PCR) and the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). All steps of RT-PCR and qRT-PCR should be strictly controlled to ensure the validity of obtained results. False-negative results may be caused not only by inhibition of RT or/and PCR steps but also by failure of the nucleic acid extraction step, particularly in the case of viral RNA extraction. The control of nucleic acid extraction generally involves the utilization of a non-pathogenic virus (process control virus) of similar structural properties to those of the target virus. Although in clinical samples the use of such process control virus is only recommended, in other kinds of settings such as food matrices its use is necessary. Currently, several different process control viruses are used for these purposes. Process control viruses can also be constructed artificially using technology for production of MS2 phage-like particles, which have many advantages in comparison with other used controls and are especially suited for controlling the detection and quantification of certain types of RNA viruses. The technology for production of MS2 phage-like particles is theoretically well established, uses the knowledge gained from the study of the familiar bacteriophage MS2 and utilizes many different approaches for the construction of the various process control viruses. Nevertheless, the practical use of MS2 phage-like particles in routine diagnostics is relatively uncommon. The current situation with regard to the use of MS2 phage-like particles as process control viruses in detection of RNA viruses and different methods of their construction, purification and use are summarized and discussed in this review.

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“…The clear lysate was centrifuged at 5000 g for 10 min to remove remaining cells and cell debris. When necessary, cyanophages were further concentrated either by precipitation with 10-15% (w ⁄ v) polyethylene glycol (PEG 6000, Fisher Scientific, Loughborough, U.K.) or by ultracentrifugation at 80 000 g for 120 min at 4°C (adapted from Børsheim et al, 1990) and resuspension of the pellet in 0.1· of the original volume of CP buffer.…”

Section: Cyanophage Concentrationmentioning

confidence: 99%

“…Viruses are the most abundant biological entities in aquatic systems (Suttle, 2005) and bacteriophages are the most common viruses (Børsheim, Bratbak & Heldal, 1990;Bratbak et al, 1990;Wommack & Colwell, 2000;Alonso et al, 2001). Given the numbers of cyanobacteria within the bacterioplankton, it may not be surprising to find that cyanophages are both widespread and abundant.…”

Section: Introductionmentioning

confidence: 99%

Evidence for cyanophages active against bloom‐forming freshwater cyanobacteria

Deng

Hayes

2008

Freshwater Biology

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1. A total of 35 putative cyanophages able to infect non-axenic cultures of bloom-forming freshwater cyanobacteria in the genera Microcystis, Anabaena and Planktothrix were isolated from Lake Zurich (Switzerland) and lakes in the Cotswold Water Park (U.K.). Eleven lytic cyanophage isolates were isolated on Microcystis and 12 each on Anabaena and Planktothrix. Cyanophage isolation protocols varied when using these different cyanobacterial hosts. 2. The collection of putative cyanophage isolates encompassed a variety of morphotypes, including the first filamentous cyanophage from any environment and the second siphocyanophage reported from fresh water. 3. PCR primer sets for gp20, gp23 and MCP genes, which have been previously found to be conserved in other cyanophages, were used in an attempt to determine genetic diversity among the phage isolates. The failure to obtain specific amplification products from most isolates suggests that the cyanophages isolated in this study were different from those previously characterized from both marine and freshwater environments. 4. Some putative cyanophages within the collection of isolates proved to have a very broad host range and were able to infect Anabaena, Microcystis and Planktothrix. The ability to infect a wide range of host taxa extends the potential reproductive period for lytic propagation, and also has implications for the transfer of genetic information between deeply separated cyanobacterial lineages.

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Enumeration and biomass estimation of planktonic bacteria and viruses by transmission electron microscopy

Cited by 276 publications

References 31 publications

Ecology of prokaryotic viruses

Ecology of prokaryotic viruses

Methods for Preparation of MS2 Phage-Like Particles and Their Utilization as Process Control Viruses in RT-PCR and qRT-PCR Detection of RNA Viruses From Food Matrices and Clinical Specimens

Evidence for cyanophages active against bloom‐forming freshwater cyanobacteria

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