A grassland soil virus-host community whose dynamics were measured following rewetting of a seasonally dry California Mediterranean-climate soil. Dry soil holds a diverse but low-biomass reservoir of virions, of which only a subset thrives following wet-up. Quantitative isotope tracing, time-resolved metagenomics, and viromics show viral richness declines by 50 percent within 24 hours post wet-up while viral biomass increases four-fold within one week. Lytic, not lysogenic, cycles dominate the response. Viruses drive a measurable and continuous rate of cell lysis, accounting for up to 46 percent of microbial death one week after wet-up, contributing to microbial biomass turnover and the widely reported post-wet-up CO2 efflux.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| soil DNA viruses (virions) — ontology label: Viruses | NCBITaxon:10239 · TaxonMech · TraitMech | N/A | |
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| grassland soil bacterial hosts — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
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N/A |
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
Lytic-Dominated Viral Response Inferred After Wet-Up
Laboratory wet-up microcosms showed viral richness loss and increasing viral-DNA biomass proxies, with isotope incorporation supporting active viral DNA replication. The authors infer a predominantly lytic response from these measurements and lifestyle markers. This positive evidence does not exclude nonintegrating temperate lifestyles or directly count every productive infection. The abstract reports a 50% richness decline within 24 h and a four-fold biomass increase within one week; the main Results summarize richness loss over the week. Those time-window summaries need not conflict; no independent reconstruction of the time course is claimed here.
Participating Taxa: soil DNA viruses (virions), grassland soil bacterial hosts
Biological Processes:
- virus-host interaction (GO:0044003 · PathwayMech)
PARTIAL - productive lytic infection would cause host death. Viral replication, particle dynamics and lifestyle markers support this contribution, but the magnitude is inferred using burst-size and recovery assumptions rather than directly resolved infection-to-death events.
Evidence
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PMID:37730729 - PARTIAL (COMPUTATIONAL)"viruses in lytic cycles dominate the response to wet-up"
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PMID:37730729 - SUPPORT (IN_VITRO)"Viral richness decreases by 50% within 24 h post wet-up, while viral biomass increases four-fold within one week"
Estimated Viral Contribution to Microbial Death
PREDATIONThe study estimates a viral contribution to bacterial mortality from extracellular viral DNA and a separately estimated bacterial-death denominator. Its cumulative one-week estimate ranges from below 1% to 46.6% as assumed burst size changes from 200 to 1 virions per cell. This is a model-dependent inference, not directly counted lysis of 46% of all microbes. The estimate depends on viral genome length, extraction recovery, particle persistence and assumptions about bacterial rRNA gene copies. Canonical virus-to-bacterium direction denotes the proposed aggregate predatory process, not resolved strain-specific host links.
Source Taxon: soil DNA viruses (virions)
Target Taxon: grassland soil bacterial hosts
Biological Processes:
- virus-host interaction (GO:0044003 · PathwayMech)
HYPOTHESIZED - lysis-released cellular carbon could support turnover and community respiration. The study does not isolate the viral share of CO2 efflux or selectively establish this carbon-transfer mediation.
Evidence
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PMID:37730729 - PARTIAL (COMPUTATIONAL)"up to 46% of microbial death driven by viral lysis one week following wet-up"
Inferred Lysis Contribution to Biomass Turnover and CO2 Efflux
HYPOTHESIZED - lysis can release cellular material that contributes to soil biomass turnover and potentially fuels respiration after wet-up. The paper interprets its viral dynamics and mortality estimates in this ecosystem context; it does not selectively isolate virus-driven CO2 flux or establish this pathway as the cause of the whole wet-up respiration pulse.
Participating Taxa: soil DNA viruses (virions), grassland soil bacterial hosts
Metabolites: carbon dioxide (CHEBI:16526 · MediaIngredientMech · CMMMech)
Evidence
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PMID:37730729 - PARTIAL (COMPUTATIONAL)"viruses contribute to turnover of soil microbial biomass and the widely reported CO2 efflux following wet-up of seasonally dry soils"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How much wet-up mortality and respiratory carbon flux are caused by viruses?
Resolve burst size, genome-length conversion, extraction efficiency, persistent particles and the assumed six bacterial 16S copies per cell before assigning a fixed mortality fraction. The Results and Discussion give slightly different lower bounds, both below 1%; no equation or analysis-code reimplementation is claimed. Separate early osmotic mortality from later viral effects. Genomic lifestyle markers do not exclude nonintegrating temperate infections, and coarse host predictions do not identify every infected strain. Direct viral perturbations and carbon tracing are needed for the proposed CO2 mediation. Abstract and main-body richness summaries use different time windows, which need not be contradictory. Preserve all positive time-course evidence while retaining these uncertainty labels; non-graph metadata is not recertified.
Attaches to: ecological_interactions#Lytic-Dominated Viral Response Inferred After Wet-Up, ecological_interactions#Estimated Viral Contribution to Microbial Death, ecological_interactions#Inferred Lysis Contribution to Biomass Turnover and CO2 Efflux
External Resources
| Name | Repository | Resource ID |
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Primary publication for the grassland wet-up virus-host community
PubMed record for the Nicolas et al. 2023 Nat Commun paper on soil viruses thriving following microbial resuscitation during rewetting. |
OTHER | PMID:37730729 |
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DOI landing page
DOI link to the Nature Communications paper. |
OTHER | doi:10.1038/s41467-023-40835-4 |
Environmental Factors
| Factor | Value | Unit |
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| Wet-up event | prolonged dry period followed by laboratory rewetting | N/A |
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| Time course post wet-up | 24 h to one week post wet-up | N/A |
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