Enhancement of viral production by addition of nitrogen or nitrogen plus carbon in subtropical surface waters of the South Pacific

Motegi, Chiaki; Nagata, Toshi

doi:10.3354/ame048027

Cited by 32 publications

(38 citation statements)

References 40 publications

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“…The production of viruses in response to carbon and nitrate addition is consistent with previous studies, demonstrating that amendments of organic carbon and/or inorganic nutrients stimulated viral production in pelagic systems (Tuomi et al, 1995;Noble and Fuhrman, 1999;Hewson et al, 2001;Weinbauer et al, 2003;Motegi and Nagata, 2007). However, in our studies, organic carbon alone did not result in significant viral production and required the addition of a terminal electron acceptor (nitrate).…”

Section: Discussionsupporting

confidence: 92%

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

et al. 2014

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A variety of microbially mediated metabolic pathways impact biogeochemical cycling in terrestrial subsurface environments. However, the role that viruses have in influencing microbial mortality and microbial community structure is poorly understood. Here we investigated the production of viruses and change in microbial community structure within shallow alluvial aquifer sediment slurries amended with 13 C-labeled acetate and nitrate. Biostimulation resulted in production of viruses concurrent with acetate oxidation, 13 CO 2 production and nitrate reduction. Interestingly, change in viral abundance was positively correlated to acetate consumption (r 2 ¼ 0.6252, Po0.05) and 13 CO 2 production (r 2 ¼ 0.6572, Po0.05); whereas change in cell abundance was not correlated to acetate consumption or 13 CO 2 production. Viral-mediated cell lysis has implications for microbial community structure. Betaproteobacteria predominated microbial community composition (62% of paired-end reads) upon inoculation but decreased in relative abundance and was negatively correlated to changes in viral abundance (r 2 ¼ 0.5036, Po0.05). As members of the Betaproteobacteria decreased, Gammaproteobacteria, specifically Pseudomonas spp., increased in relative abundance (82% of paired-end reads) and was positively correlated with the change in viral abundance (r 2 ¼ 0.5368, Po0.05). A nitrate-reducing bacterium, Pseudomonas sp. strain Alda10, was isolated from these sediments and produced viral-like particles with a filamentous morphology that did not result in cell lysis. Together, these results indicate that viruses are linked to carbon biogeochemistry and community structure in terrestrial subsurface sediments. The subsequent cell lysis has the potential to alter available carbon pools in subsurface environments, additionally controlling microbial community structure from the bottom-up.

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Section: Discussionsupporting

confidence: 92%

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

et al. 2014

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“…Factors that may affect viral production and the extent of viral-induced bacterial mortality include the activity of host cells (Middelboe 2000). This proposition is consistent with the observation that viral production increases with increasing bacterial production or growth in response to the addition of nutrients and organic substrate (Tuomi et al 1995, Williamson & Paul 2004, Motegi & Nagata 2007.…”

Section: Introductionsupporting

confidence: 91%

“…Viral production. Viral production rate was determined by the 3 H-TdR method with enzyme digestions according to Noble & Steward (2001) with modifications (Motegi & Nagata 2007). Triplicate subsamples (7 ml each) were contained in polypropylene tubes (14 ml capacity, BD Falcon), spiked with [methyl-3 H] TdR (final concentration 10 nM) and incubated for 1 h at in situ temperature in the dark.…”

Section: Methodsmentioning

confidence: 99%

“…reduction in number or modification of receptors, development of restriction enzyme-modification system; Forde & Fitzgerald 1999, Weinbauer 2004 to reduce viralinduced mortality when resource competition is less severe. In addition, there is experimental evidence of viral loss rates increasing with increasing bacterial production from a study on nutrient enriched seawater cultures (Motegi & Nagata 2007); one possible explanation proposed was the destruction of viral capsids by extracellular proteases released by rapidly growing bacteria (e.g. Ward et al 1986, Noble & Fuhrman 1997.…”

Section: Introductionmentioning

confidence: 99%

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Addition of monomeric and polymeric organic substrates alleviates viral lytic pressure on bacterial communities in coastal seawaters

Motegi¹,

Nagata²

2009

Aquat. Microb. Ecol.

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We examined the effect of growth conditions on the fraction of bacterial production lysed by viruses (F lysed ). Time-course changes in bacterial and viral variables were determined in coastal seawater cultures with and without the addition of monomeric (glucose or amino acids) or polymeric (protein) substrates. Substrate-induced enhancement of bacterial production was much more pronounced than that of viral production during the incubation period of 60 to 90 h. Estimates of F lysed were highest in non-addition controls (range = 0.3 to 1.0), followed by the monomer addition treatment (0.1 to 0.2), and lowest in the protein addition treatment (0.04 to 0.1). These data are consistent with the proposition that bacterial communities grown under substrate-rich conditions are less subject to viral attacks. Low F lysed values in the protein addition treatment were associated with high activities of leucine aminopeptidase, indicating a role of extracellular proteases in alleviating viral lytic pressure. Our data support the notion that supplies of dissolved organic matter affect the magnitude of bacteria-virus couplings in marine environments.

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“…It is argued that an increase in the number of receptors would enhance the attachment of viruses to hosts and thus the infection rate (Lenski 1988). These mechanisms could explain the experiments in which adding nutrients to systems containing bacteria and viruses enhances viral production in various environments (Hewson et al 2001;Williamson et al 2002;Weinbauer et al 2003;Motegi and Nagata 2007), even though a negative relationship between nutrient conditions and viral activity has also been reported (Lymer et al 2008). In addition to the physiological responses of hosts and viruses to growth conditions, it is speculated that local adaptation of viruses to different trophic status may also be important.…”

Section: Trait Changes In Bacterial Assemblage and Their Consequencesmentioning

confidence: 99%

Indirect interactions in the microbial world: specificities and similarities to plant–insect systems

Miki

Jacquet²

2010

Population Ecology

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Trophic interactions between bacteria, viruses, and protozoan predators play crucial roles in structuring aquatic microbial communities and regulating microbemediated ecosystem functions (biogeochemical processes). In this microbial food web, protozoan predators and viruses share bacteria as a common resource, and protozoan predators can kill viruses [intraguild predation (IGP)] and vice versa, even though these latter processes are probably of less importance. However, protozoan predators (IG predator) and viruses (IG prey) generally occur together in various environments, and this cannot be fully explained by the classic IGP models. In addition, controlled experiments have often demonstrated that protozoan predators have apparently positive effects on viral activity. These surprising patterns can be explained by indirect interactions between them via induced trait changes in bacterial assemblages, which can be compared with trait-mediated indirect interactions (TMIIs) in terrestrial plant-insect systems. Here, we review some trait changes in bacterial assemblages that may positively affect the activities and abundance of viruses. It has been suggested that in bacterial assemblages, protozoan predation may enhance growth conditions for individual bacteria and induce both phenotypic trait changes at the individual (e.g., filament-forming bacteria) and group level as a result of changes in bacterial community composition (e.g., species dominance). We discuss the specificities of aquatic microbial systems and attempt find functional similarities between aquatic microbial systems and terrestrial plant-insect systems with regard to TMII function.

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Enhancement of viral production by addition of nitrogen or nitrogen plus carbon in subtropical surface waters of the South Pacific

Cited by 32 publications

References 40 publications

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

Addition of monomeric and polymeric organic substrates alleviates viral lytic pressure on bacterial communities in coastal seawaters

Indirect interactions in the microbial world: specificities and similarities to plant–insect systems

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