High abundance of viruses found in aquatic environments.
TL;DR: Using a new method for quantitative enumeration, up to 2.5 x IO8 virus particles per millilitre in natural waters indicate that virus infection may be an important factor in the ecological control of planktonic micro-organisms.
Abstract: The concentration of bacteriophages in natural unpolluted waters is in general believed to be low, and they have therefore been considered ecologically unimportant. Using a new method for quantitative enumeration, we have found up to 2.5 x 10(8) virus particles per millilitre in natural waters. These concentrations indicate that virus infection may be an important factor in the ecological control of planktonic micro-organisms, and that viruses might mediate genetic exchange among bacteria in natural aquatic environments.
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TL;DR: The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced the authors' understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis ofBiofilm development.
Abstract: Biofilms are complex communities of microorganisms attached to surfaces or associated with interfaces. Despite the focus of modern microbiology research on pure culture, planktonic (free-swimming) bacteria, it is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces. Furthermore, these microbial communities are often composed of multiple species that interact with each other and their environment. The determination of biofilm architecture, particularly the spatial arrangement of microcolonies (clusters of cells) relative to one another, has profound implications for the function of these complex communities. Numerous new experimental approaches and methodologies have been developed in order to explore metabolic interactions, phylogenetic groupings, and competition among members of the biofilm. To complement this broad view of biofilm ecology, individual organisms have been studied using molecular genetics in order to identify the genes required for biofilm development and to dissect the regulatory pathways that control the plankton-to-biofilm transition. These molecular genetic studies have led to the emergence of the concept of biofilm formation as a novel system for the study of bacterial development. The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced our understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis of biofilm development.
2,910 citations
Cites background from "High abundance of viruses found in ..."
...In the late 1980s, it was discovered that there is a very high abundance of viruses (as high as 10(8) per ml) in both limnetic (fresh water) and marine systems and that the majority of these viruses are bacteriophages (13, 202)....
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TL;DR: Viruses are by far the most abundant 'lifeforms' in the oceans and are the reservoir of most of the genetic diversity in the sea, thereby driving the evolution of both host and viral assemblages.
Abstract: If stretched end to end, the estimated 1030viruses in the oceans would span farther than the nearest 60 galaxies. This reservoir of genetic and biological diversity continues to yield exciting discoveries and, in this Review, Curtis A. Suttle highlights the areas that are likely to be of greatest interest in the next few years. Viruses are by far the most abundant 'lifeforms' in the oceans and are the reservoir of most of the genetic diversity in the sea. The estimated 1030 viruses in the ocean, if stretched end to end, would span farther than the nearest 60 galaxies. Every second, approximately 1023 viral infections occur in the ocean. These infections are a major source of mortality, and cause disease in a range of organisms, from shrimp to whales. As a result, viruses influence the composition of marine communities and are a major force behind biogeochemical cycles. Each infection has the potential to introduce new genetic information into an organism or progeny virus, thereby driving the evolution of both host and viral assemblages. Probing this vast reservoir of genetic and biological diversity continues to yield exciting discoveries.
2,438 citations
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...The observation that millions of virus-like particles are present in every millilitre of ocean wate...
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TL;DR: Newly developed fluorescence and molecular techniques leave the field poised to make significant advances towards evaluating and quantifying viruses' effects on biogeochemical and ecological processes.
Abstract: Viruses are the most common biological agents in the sea, typically numbering ten billion per litre. They probably infect all organisms, can undergo rapid decay and replenishment, and influence many biogeochemical and ecological processes, including nutrient cycling, system respiration, particle size-distributions and sinking rates, bacterial and algal biodiversity and species distributions, algal bloom control, dimethyl sulphide formation and genetic transfer. Newly developed fluorescence and molecular techniques leave the field poised to make significant advances towards evaluating and quantifying such effects.
2,021 citations
TL;DR: Novel applications of molecular genetic techniques have provided good evidence that viral infection can significantly influence the composition and diversity of aquatic microbial communities, supporting the hypothesis that viruses play a significant role in microbial food webs.
Abstract: The discovery that viruses may be the most abundant organisms in natural waters, surpassing the number of bacteria by an order of magnitude, has inspired a resurgence of interest in viruses in the aquatic environment. Surprisingly little was known of the interaction of viruses and their hosts in nature. In the decade since the reports of extraordinarily large virus populations were published, enumeration of viruses in aquatic environments has demonstrated that the virioplankton are dynamic components of the plankton, changing dramatically in number with geographical location and season. The evidence to date suggests that virioplankton communities are composed principally of bacteriophages and, to a lesser extent, eukaryotic algal viruses. The influence of viral infection and lysis on bacterial and phytoplankton host communities was measurable after new methods were developed and prior knowledge of bacteriophage biology was incorporated into concepts of parasite and host community interactions. The new methods have yielded data showing that viral infection can have a significant impact on bacteria and unicellular algae populations and supporting the hypothesis that viruses play a significant role in microbial food webs. Besides predation limiting bacteria and phytoplankton populations, the specific nature of virus-host interaction raises the intriguing possibility that viral infection influences the structure and diversity of aquatic microbial communities. Novel applications of molecular genetic techniques have provided good evidence that viral infection can significantly influence the composition and diversity of aquatic microbial communities.
1,930 citations
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TL;DR: The understanding of the effect of viruses on global systems and processes continues to unfold, overthrowing the idea that viruses and virus-mediated processes are sidebars to global processes.
Abstract: Viruses exist wherever life is found. They are a major cause of mortality, a driver of global geochemical cycles and a reservoir of the greatest genetic diversity on Earth. In the oceans, viruses probably infect all living things, from bacteria to whales. They affect the form of available nutrients and the termination of algal blooms. Viruses can move between marine and terrestrial reservoirs, raising the spectre of emerging pathogens. Our understanding of the effect of viruses on global systems and processes continues to unfold, overthrowing the idea that viruses and virus-mediated processes are sidebars to global processes.
1,894 citations
Cites background from "High abundance of viruses found in ..."
...jpg" NDATA ITEM> ]> For years viruses were known to exist in seawater, but reports 15 years ago caused great excitement by demonstrating not only that viruses are abundant, but that they infect the dominant organisms in the ocea...
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References
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845 citations
TL;DR: It is suggested that bacteriophages do not affect the number or activity of bacteria in environments where the density of the host species is below the host cell threshold of about 10(4) CFU/ml.
Abstract: Bacteriophage 80 alpha did not increase in number in cultures containing less than about 1.0 X 10(4) to 1.5 X 10(4) CFU of Staphylococcus aureus per ml, but bacteriophage replication did occur when the number of bacteria exceeded this density, either initially or as a result of host cell multiplication. The minimum density of an asporogenous strain of Bacillus subtilis required for an increase in the number of bacteriophage SP beta cI was about 3 X 10(4) CFU/ml. The threshold density of Escherichia coli for the multiplication of bacteriophage T4 was about 7 X 10(3) CFU/ml. In the presence of montmorillonite, bacteriophage T4 did not increase in number until the E. coli population exceeded 10(4) CFU/ml. The mineralization of glucose was not affected in E. coli cultures inoculated with a low number of bacteriophage T4, but it could not be detected in cultures inoculated with a large number of phage. The numbers of bacteriophage T4 and a bacteriophage that lyses Pseudomonas putida declined rapidly after being added to lake water or sewage. We suggest that bacteriophages do not affect the number or activity of bacteria in environments where the density of the host species is below the host cell threshold of about 10(4) CFU/ml.
259 citations
TL;DR: Results obtained from river water, estuarine water, and seawater show overall bacterial mortality rates in the range 0.010 to 0.030 h, in good agreement with the range of growth rates measured in the same environments.
Abstract: A method is proposed which provides a minimum estimate of the rate of bacterial mortality in growing natural populations of planktonic bacteria. This estimate is given by the rate of decrease of radioactivity from the DNA of a [3H]thymidine-labeled natural assemblage of bacteria after all added thymidine has been exhausted from the medium. Results obtained from river water, estuarine water, and seawater show overall bacterial mortality rates in the range 0.010 to 0.030 h−1, in good agreement with the range of growth rates measured in the same environments. Use of selective filtration through Nuclepore filters (pore size, 2 μm) allowed us to determine the contribution of microzooplankton grazing to overall bacterial mortality. Grazing rates estimated by this method ranged from 0 to 0.02 h−1.
153 citations
TL;DR: Evidence is presented that previously uncharacterized, small eukaryotes that are able to pass even 0.6-micrometer filters may be responsible for a large fraction of the total grazing in coastal waters.
Abstract: Up to 60 percent of the total marine primary production (or about one-fourth of the total global carbon dioxide fixation) passes through the free-living bacterioplankton. Grazing by bacteriovores is probably the predominant fate of the bacteria, although data are scarce. Evidence is presented that previously uncharacterized, small eukaryotes that are able to pass even 0.6-micrometer filters may be responsible for a large fraction (more than 50 percent) of the total grazing in coastal waters. These organisms have not yet been observed microscopically.
135 citations