Viral activity in lake analogs of anoxic early Earth oceans
Abstract Background Meromictic lakes, with their stratified water columns, are modern analogs for ancient euxinic (anoxic and sulfidic) oceans, where anaerobic sulfur-oxidizing purple and green sulfur bacteria (PSB and GSB) dominated as primary producers. Recent studies suggest a potential role of v...
Saved in:
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2025-04-01
|
| Series: | Microbiome |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40168-025-02085-y |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850139137523318784 |
|---|---|
| author | Natascha S. Varona Bailey A. Wallace Alice Bosco-Santos Julianna Mullinax Alexandra K. Stiffler Molly D. O’Beirne Josh Ford James M. Fulton Josef P. Werne William P. Gilhooly Cynthia B. Silveira |
| author_facet | Natascha S. Varona Bailey A. Wallace Alice Bosco-Santos Julianna Mullinax Alexandra K. Stiffler Molly D. O’Beirne Josh Ford James M. Fulton Josef P. Werne William P. Gilhooly Cynthia B. Silveira |
| author_sort | Natascha S. Varona |
| collection | DOAJ |
| description | Abstract Background Meromictic lakes, with their stratified water columns, are modern analogs for ancient euxinic (anoxic and sulfidic) oceans, where anaerobic sulfur-oxidizing purple and green sulfur bacteria (PSB and GSB) dominated as primary producers. Recent studies suggest a potential role of viruses in the metabolisms and biosignatures of these bacteria, but conclusive evidence of viral replication and activity in such lakes is still lacking. Results Here, we investigate viral activity in the upper mixed layer (mixolimnion), the anoxic bottom (monimolimnion), and the microbial plate (a dense layer of phototrophic sulfur bacteria forming at the boundary between the oxygenated mixolimnion and the anoxic monimolimnion) of three meromictic lakes: Poison and Lime Blue Lakes (WA, USA) and Mahoney Lake (BC, CA). Geochemical profiles of two lakes, Mahoney and Poison, which are dominated by PSB, show a sharp chemocline, whereas Lime Blue displays a less steep chemical gradient and hosts a mixture of PSB and GSB. Viral gene transcription and epifluorescence microscopy revealed depth-dependent patterns in viral activity. The two strongly stratified, PSB-dominated lakes showed a significant decrease in the virus-to-microbe ratio (VMR) in their microbial plates, suggesting reduced viral particle production via lysis. Metatranscriptome data corroborated this trend by showing lower levels of viral gene expression in these microbial plates, higher expression of CRISPR defense and lysogeny-related genes, and relatively high expression of photosynthesis-related viral genes. Conversely, the third lake, which harbors a mix of PSB and GSB, exhibited low microbial density, high VMR, and high viral transcriptional activity. Viral transcription levels significantly correlated with VMR in the microbial plates and bottom layers, but this relationship was absent in low-density, oxic surface samples. Conclusions Here, two independent lines of evidence, abundances and gene expression, show reduced viral lytic production in microbial plates dominated by PSB in stratified lakes. This suggests that viral lysis may contribute less to bacterial community structuring in these high-density microbial plates. Rather, other viral-mediated mechanisms, such as lysogeny and the expression of auxiliary metabolic genes, may represent a more significant viral influence on bacterial physiology and geochemistry. These patterns in virus-bacteria interactions may be consequential for the interpretations of biosignatures left by these bacterial groups in the geologic record. Video Abstract |
| format | Article |
| id | doaj-art-30a60c828a684811bddf8eff10f85692 |
| institution | OA Journals |
| issn | 2049-2618 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | BMC |
| record_format | Article |
| series | Microbiome |
| spelling | doaj-art-30a60c828a684811bddf8eff10f856922025-08-20T02:30:24ZengBMCMicrobiome2049-26182025-04-0113111610.1186/s40168-025-02085-yViral activity in lake analogs of anoxic early Earth oceansNatascha S. Varona0Bailey A. Wallace1Alice Bosco-Santos2Julianna Mullinax3Alexandra K. Stiffler4Molly D. O’Beirne5Josh Ford6James M. Fulton7Josef P. Werne8William P. Gilhooly9Cynthia B. Silveira10Department of Biology, University of MiamiDepartment of Biology, University of MiamiInstitute of Earth Surface Dynamics, University of LausanneDepartment of Biology, University of MiamiDepartment of Biology, University of MiamiDepartment of Geology & Environmental Science, University of PittsburghGeosciences Department, Baylor UniversityGeosciences Department, Baylor UniversityDepartment of Geology & Environmental Science, University of PittsburghDepartment of Earth & Environmental Sciences, Indiana University IndianapolisDepartment of Biology, University of MiamiAbstract Background Meromictic lakes, with their stratified water columns, are modern analogs for ancient euxinic (anoxic and sulfidic) oceans, where anaerobic sulfur-oxidizing purple and green sulfur bacteria (PSB and GSB) dominated as primary producers. Recent studies suggest a potential role of viruses in the metabolisms and biosignatures of these bacteria, but conclusive evidence of viral replication and activity in such lakes is still lacking. Results Here, we investigate viral activity in the upper mixed layer (mixolimnion), the anoxic bottom (monimolimnion), and the microbial plate (a dense layer of phototrophic sulfur bacteria forming at the boundary between the oxygenated mixolimnion and the anoxic monimolimnion) of three meromictic lakes: Poison and Lime Blue Lakes (WA, USA) and Mahoney Lake (BC, CA). Geochemical profiles of two lakes, Mahoney and Poison, which are dominated by PSB, show a sharp chemocline, whereas Lime Blue displays a less steep chemical gradient and hosts a mixture of PSB and GSB. Viral gene transcription and epifluorescence microscopy revealed depth-dependent patterns in viral activity. The two strongly stratified, PSB-dominated lakes showed a significant decrease in the virus-to-microbe ratio (VMR) in their microbial plates, suggesting reduced viral particle production via lysis. Metatranscriptome data corroborated this trend by showing lower levels of viral gene expression in these microbial plates, higher expression of CRISPR defense and lysogeny-related genes, and relatively high expression of photosynthesis-related viral genes. Conversely, the third lake, which harbors a mix of PSB and GSB, exhibited low microbial density, high VMR, and high viral transcriptional activity. Viral transcription levels significantly correlated with VMR in the microbial plates and bottom layers, but this relationship was absent in low-density, oxic surface samples. Conclusions Here, two independent lines of evidence, abundances and gene expression, show reduced viral lytic production in microbial plates dominated by PSB in stratified lakes. This suggests that viral lysis may contribute less to bacterial community structuring in these high-density microbial plates. Rather, other viral-mediated mechanisms, such as lysogeny and the expression of auxiliary metabolic genes, may represent a more significant viral influence on bacterial physiology and geochemistry. These patterns in virus-bacteria interactions may be consequential for the interpretations of biosignatures left by these bacterial groups in the geologic record. Video Abstracthttps://doi.org/10.1186/s40168-025-02085-yBacteriophageViral activityMeromictic lakeViral metatranscriptomics |
| spellingShingle | Natascha S. Varona Bailey A. Wallace Alice Bosco-Santos Julianna Mullinax Alexandra K. Stiffler Molly D. O’Beirne Josh Ford James M. Fulton Josef P. Werne William P. Gilhooly Cynthia B. Silveira Viral activity in lake analogs of anoxic early Earth oceans Microbiome Bacteriophage Viral activity Meromictic lake Viral metatranscriptomics |
| title | Viral activity in lake analogs of anoxic early Earth oceans |
| title_full | Viral activity in lake analogs of anoxic early Earth oceans |
| title_fullStr | Viral activity in lake analogs of anoxic early Earth oceans |
| title_full_unstemmed | Viral activity in lake analogs of anoxic early Earth oceans |
| title_short | Viral activity in lake analogs of anoxic early Earth oceans |
| title_sort | viral activity in lake analogs of anoxic early earth oceans |
| topic | Bacteriophage Viral activity Meromictic lake Viral metatranscriptomics |
| url | https://doi.org/10.1186/s40168-025-02085-y |
| work_keys_str_mv | AT nataschasvarona viralactivityinlakeanalogsofanoxicearlyearthoceans AT baileyawallace viralactivityinlakeanalogsofanoxicearlyearthoceans AT aliceboscosantos viralactivityinlakeanalogsofanoxicearlyearthoceans AT juliannamullinax viralactivityinlakeanalogsofanoxicearlyearthoceans AT alexandrakstiffler viralactivityinlakeanalogsofanoxicearlyearthoceans AT mollydobeirne viralactivityinlakeanalogsofanoxicearlyearthoceans AT joshford viralactivityinlakeanalogsofanoxicearlyearthoceans AT jamesmfulton viralactivityinlakeanalogsofanoxicearlyearthoceans AT josefpwerne viralactivityinlakeanalogsofanoxicearlyearthoceans AT williampgilhooly viralactivityinlakeanalogsofanoxicearlyearthoceans AT cynthiabsilveira viralactivityinlakeanalogsofanoxicearlyearthoceans |