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McKindles KM, Manes M, Neudeck M, McKay RM, Bullerjahn GS. Multi-year molecular quantification and 'omics analysis of Planktothrix-specific cyanophage sequences from Sandusky Bay, Lake Erie. Front Microbiol 2023; 14:1199641. [PMID: 37455749 PMCID: PMC10343443 DOI: 10.3389/fmicb.2023.1199641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 06/08/2023] [Indexed: 07/18/2023] Open
Abstract
Introduction Planktothrix agardhii is a microcystin-producing cyanobacterium found in Sandusky Bay, a shallow and turbid embayment of Lake Erie. Previous work in other systems has indicated that cyanophages are an important natural control factor of harmful algal blooms. Currently, there are few cyanophages that are known to infect P. agardhii, with the best-known being PaV-LD, a tail-less cyanophage isolated from Lake Donghu, China. Presented here is a molecular characterization of Planktothrix specific cyanophages in Sandusky Bay. Methods and Results Putative Planktothrix-specific viral sequences from metagenomic data from the bay in 2013, 2018, and 2019 were identified by two approaches: homology to known phage PaV-LD, or through matching CRISPR spacer sequences with Planktothrix host genomes. Several contigs were identified as having viral signatures, either related to PaV-LD or potentially novel sequences. Transcriptomic data from 2015, 2018, and 2019 were also employed for the further identification of cyanophages, as well as gene expression of select viral sequences. Finally, viral quantification was tested using qPCR in 2015-2019 for PaV-LD like cyanophages to identify the relationship between presence and gene expression of these cyanophages. Notably, while PaV-LD like cyanophages were in high abundance over the course of multiple years (qPCR), transcriptomic analysis revealed only low levels of viral gene expression. Discussion This work aims to provide a broader understanding of Planktothrix cyanophage diversity with the goals of teasing apart the role of cyanophages in the control and regulation of harmful algal blooms and designing monitoring methodology for potential toxin-releasing lysis events.
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Affiliation(s)
- Katelyn M. McKindles
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, United States
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
- Great Lakes Center for Fresh Waters and Human Health, Bowling Green State University, Bowling Green, OH, United States
| | - Makayla Manes
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
| | - Michelle Neudeck
- Great Lakes Center for Fresh Waters and Human Health, Bowling Green State University, Bowling Green, OH, United States
| | - Robert Michael McKay
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
- Great Lakes Center for Fresh Waters and Human Health, Bowling Green State University, Bowling Green, OH, United States
| | - George S. Bullerjahn
- Great Lakes Center for Fresh Waters and Human Health, Bowling Green State University, Bowling Green, OH, United States
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Shaalan H, Cattan-Tsaushu E, Li K, Avrani S. Sequencing the genomes of LPP-1, the first isolated cyanophage, and its relative LPP-2 reveal different integration mechanisms in closely related phages. HARMFUL ALGAE 2023; 124:102409. [PMID: 37164560 DOI: 10.1016/j.hal.2023.102409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/16/2023] [Accepted: 02/18/2023] [Indexed: 05/12/2023]
Abstract
In the early 1960s, the first cyanophage was isolated. The description of this phage, named LPP-1, led to the extensive investigation of various cyanophages and to the study of their interactions with their cyanobacterial hosts towards controlling blooms. Here, the genomes of LPP-1 and its putative relative, LPP-2 were sequenced. Sequencing these genomes revealed that LPP-1 and LPP-2 are members of a group of short-tailed cyanophages, which are distantly related to the T7-like cyanophages. Most of the phages in this group have the ability to lysogenize their hosts. Their ability to switch between lytic and lysogenic infection may explain the formation of cyanobacterial blooms despite the persistence of their phages. This lysogenic capacity of the LPP-1-like phages occurs despite the lack of an obvious integrase gene within their genomes. Interestingly, we show that LPP-2 integrates into the host genome through an integration site in high proximity to a recombination endonuclease that may have integrase activity. Further understanding of cyanobacterial-phage relationships may provide insight into their population dynamics and suggest novel approaches for control of destructive cyanobacterial blooms.
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Affiliation(s)
- Hanaa Shaalan
- Department of Evolutionary and Environmental Biology and The Institute of Evolution, University of Haifa, Haifa, Israel
| | - Eti Cattan-Tsaushu
- Department of Evolutionary and Environmental Biology and The Institute of Evolution, University of Haifa, Haifa, Israel
| | - Ke Li
- Department of Evolutionary and Environmental Biology and The Institute of Evolution, University of Haifa, Haifa, Israel
| | - Sarit Avrani
- Department of Evolutionary and Environmental Biology and The Institute of Evolution, University of Haifa, Haifa, Israel.
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3
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Peng K, Jiao Y, Gao J, Xiong W, Zhao Y, Yang S, Liao M. Viruses may facilitate the cyanobacterial blooming during summer bloom succession in Xiangxi Bay of Three Gorges Reservoir, China. Front Microbiol 2023; 14:1112590. [PMID: 36970686 PMCID: PMC10030618 DOI: 10.3389/fmicb.2023.1112590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/13/2023] [Indexed: 03/11/2023] Open
Abstract
The occurrence of cyanobacterial blooms in summer are frequently accompanied by the succession of phytoplankton communities in freshwater. However, little is known regarding the roles of viruses in the succession, such as in huge reservoirs. Here, we investigated the viral infection characteristics of phytoplankton and bacterioplankton during the summer bloom succession in Xiangxi Bay of Three Gorges Reservoir, China. The results indicated that three distinct bloom stages and two successions were observed. From cyanobacteria and diatom codominance to cyanobacteria dominance, the first succession involved different phyla and led to a Microcystis bloom. From Microcystis dominance to Microcystis and Anabaena codominance, the second succession was different Cyanophyta genera and resulted in the persistence of cyanobacterial bloom. The structural equation model (SEM) showed that the virus had positive influence on the phytoplankton community. Through the Spearman’s correlation and redundancy analysis (RDA), we speculated that both the increase of viral lysis in the eukaryotic community and the increase of lysogeny in cyanobacteria may contributed to the first succession and Microcystis blooms. In addition, the nutrients supplied by the lysis of bacterioplankton might benefit the second succession of different cyanobacterial genera and sustain the dominance of cyanobacteria. Based on hierarchical partitioning method, the viral variables still have a marked effect on the dynamics of phytoplankton community, although the environmental attributes were the major factors. Our findings suggested that viruses played multiple potential roles in summer bloom succession and may help the blooms success of cyanobacteria in Xiangxi Bay. Under the background of increasingly serious cyanobacterial blooms worldwide, our study may have great ecological and environmental significance for understanding the population succession in phytoplankton and controlling the cyanobacterial blooms.
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Affiliation(s)
- Kaida Peng
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Yiying Jiao
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Jian Gao
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Wen Xiong
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Yijun Zhao
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Shao Yang
- School of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Mingjun Liao
- Hubei Key Laboratory of Ecological Restoration for River-Lakes and Algal Utilization, School of Civil and Environmental Engineering, Hubei University of Technology, Wuhan, Hubei, China
- *Correspondence: Mingjun Liao,
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4
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Ecological Dynamics of Broad- and Narrow-Host-Range Viruses Infecting the Bloom-Forming Toxic Cyanobacterium Microcystis aeruginosa. Appl Environ Microbiol 2023; 89:e0211122. [PMID: 36688685 PMCID: PMC9972985 DOI: 10.1128/aem.02111-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Microcystis aeruginosa is predicted to interact and coexist with diverse broad- and narrow-host-range viruses within a bloom; however, little is known about their affects on Microcystis population dynamics. Here, we developed a real-time PCR assay for the quantification of these viruses that have different host ranges. During the sampling period, total Microcystis abundance showed two peaks in May and August with a temporary decrease in June. The Microcystis population is largely divided into three phylotypes based on internal transcribed sequences (ITS; ITS types I to III). ITS I was the dominant phylotype (66% to 88%) except in June. Although the ITS II and III phylotypes were mostly less abundant, these phylotypes temporarily increased to approximately equivalent abundances of the ITS I population in June. During the same sampling period, the abundances of the broad-host-range virus MVGF_NODE331 increased from April to May and from July to October with a temporary decrease in June, in which its dynamics were in proportion to the increase of total Microcystis abundances regardless of changes in host ITS population composition. In contrast, the narrow-host-range viruses MVG_NODE620 and Ma-LMM01 were considerably less abundant than the broad-host-range virus and generally did not fluctuate in the environment. Considering that M. aeruginosa could increase the abundance and sustain the bloom under the prevalence of the broad-host-range virus, host abundant and diverse antiviral mechanisms might contribute to coexistence with its viruses. IMPORTANCE The bloom-forming toxic cyanobacterium Microcystis aeruginosa interacts with diverse broad- and narrow-host-range viruses. However, the dynamics of the Microcystis population (at the intraspecies level) and viruses with different host ranges remain unknown. Our real-time PCR assays unveiled that the broad-host-range virus gradually increased in abundance over the sampling period, in proportion to the increase in total Microcystis abundance regardless of changes in genotypic composition. The narrow-host-range viruses were considerably less abundant than the broad-host-range virus and did not generally fluctuate in the environment. The expansion and maintenance of the Microcystis bloom even under the increased infection by the broad-host-range virus suggested that highly abundant and diverse antiviral mechanisms allowed them to coexist with viruses under selective pressure. This paper expands our knowledge about the ecological dynamics of Microcystis viruses and provides potential insights into their coexistence with their host.
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5
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Zepernick BN, Wilhelm SW, Bullerjahn GS, Paerl HW. Climate change and the aquatic continuum: A cyanobacterial comeback story. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:3-12. [PMID: 36096485 PMCID: PMC10103762 DOI: 10.1111/1758-2229.13122] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/11/2022] [Indexed: 05/20/2023]
Abstract
Billions of years ago, the Earth's waters were dominated by cyanobacteria. These microbes amassed to such formidable numbers, they ushered in a new era-starting with the Great Oxidation Event-fuelled by oxygenic photosynthesis. Throughout the following eon, cyanobacteria ceded portions of their global aerobic power to new photoautotrophs with the rise of eukaryotes (i.e. algae and higher plants), which co-existed with cyanobacteria in aquatic ecosystems. Yet while cyanobacteria's ecological success story is one of the most notorious within our planet's biogeochemical history, scientists to this day still seek to unlock the secrets of their triumph. Now, the Anthropocene has ushered in a new era fuelled by excessive nutrient inputs and greenhouse gas emissions, which are again reshaping the Earth's biomes. In response, we are experiencing an increase in global cyanobacterial bloom distribution, duration, and frequency, leading to unbalanced, and in many instances degraded, ecosystems. A critical component of the cyanobacterial resurgence is the freshwater-marine continuum: which serves to transport blooms, and the toxins they produce, on the premise that "water flows downhill". Here, we identify drivers contributing to the cyanobacterial comeback and discuss future implications in the context of environmental and human health along the aquatic continuum. This Minireview addresses the overlooked problem of the freshwater to marine continuum and the effects of nutrients and toxic cyanobacterial blooms moving along these waters. Marine and freshwater research have historically been conducted in isolation and independently of one another. Yet, this approach fails to account for the interchangeable transit of nutrients and biology through and between these freshwater and marine systems, a phenomenon that is becoming a major problem around the globe. This Minireview highlights what we know and the challenges that lie ahead.
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Affiliation(s)
- Brittany N. Zepernick
- Department of MicrobiologyThe University of Tennessee KnoxvilleKnoxvilleTennesseeUSA
| | - Steven W. Wilhelm
- Department of MicrobiologyThe University of Tennessee KnoxvilleKnoxvilleTennesseeUSA
| | - George S. Bullerjahn
- NIEHS/NSF Great Lakes Center for Fresh Waters and Human HealthBowling Green State UniversityBowling GreenOhioUSA
| | - Hans W. Paerl
- Institute of Marine SciencesUniversity of North Carolina at Chapel HillMorehead CityNorth CarolinaUSA
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6
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Che R, Bai M, Xiao W, Zhang S, Wang Y, Cui X. Nutrient levels and prokaryotes affect viral communities in plateau lakes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 839:156033. [PMID: 35597355 DOI: 10.1016/j.scitotenv.2022.156033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/30/2022] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Viruses are the most abundant organisms in aquatic environments. Recent advances of viral metagenomic have greatly expanded our understanding of aquatic viral communities. However, little is known about the difference of viral communities and driving factors in freshwater lake. This study seeks to understand the spatio-temporal variation, differences, and driving factors of viral communities in two plateau lakes (Dianchi and Fuxian Lakes) with significant nutritional differences. The viral communities exhibited apparent seasonal variation in Dianchi Lake, while seasonal influences on the viral communities were greater than location-based influences. Two-thirds of all detected viral taxa were shared in two lakes, but there was variation in the composition of viral communities. Correlations between prokaryotic communities, environmental factors and viral communities were analyzed. The nutrients, chlorophyll a were primarily environmental parameters affecting viral communities, and the prokaryotic community was significantly correlated with the viral community. In addition, several viruses infecting humans were identified in two lakes, with the most abundant being Herpesviridae and Poxviridae. Overall, these findings provide information on the dynamics, composition, and differences of viral and prokaryotic communities in plateau lakes with different nutrient levels. These results suggest that nutritional levels and prokaryotic communities could play an important role in shaping viral communities in freshwater lakes.
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Affiliation(s)
- Raoqiong Che
- Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Meng Bai
- Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Wei Xiao
- Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, Kunming 650091, China.
| | - Shiying Zhang
- Yunnan Engineering Laboratory of Soil Fertility and Pollution Remediation, Yunnan Agricultural University, Kunming 650201, China
| | - Yongxia Wang
- Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Xiaolong Cui
- Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, Kunming 650091, China.
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7
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The Life Cycle Transitions of Temperate Phages: Regulating Factors and Potential Ecological Implications. Viruses 2022; 14:v14091904. [PMID: 36146712 PMCID: PMC9502458 DOI: 10.3390/v14091904] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/25/2022] [Accepted: 08/25/2022] [Indexed: 11/17/2022] Open
Abstract
Phages are viruses that infect bacteria. They affect various microbe-mediated processes that drive biogeochemical cycling on a global scale. Their influence depends on whether the infection is lysogenic or lytic. Temperate phages have the potential to execute both infection types and thus frequently switch their infection modes in nature, potentially causing substantial impacts on the host-phage community and relevant biogeochemical cycling. Understanding the regulating factors and outcomes of temperate phage life cycle transition is thus fundamental for evaluating their ecological impacts. This review thus systematically summarizes the effects of various factors affecting temperate phage life cycle decisions in both culturable phage-host systems and natural environments. The review further elucidates the ecological implications of the life cycle transition of temperate phages with an emphasis on phage/host fitness, host-phage dynamics, microbe diversity and evolution, and biogeochemical cycles.
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8
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Pound HL, Martin RM, Zepernick BN, Christopher CJ, Howard SM, Castro HF, Campagna SR, Boyer GL, Bullerjahn GS, Chaffin JD, Wilhelm SW. Changes in Microbiome Activity and Sporadic Viral Infection Help Explain Observed Variability in Microcosm Studies. Front Microbiol 2022; 13:809989. [PMID: 35369463 PMCID: PMC8966487 DOI: 10.3389/fmicb.2022.809989] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
The environmental conditions experienced by microbial communities are rarely fully simulated in the laboratory. Researchers use experimental containers ("bottles"), where natural samples can be manipulated and evaluated. However, container-based methods are subject to "bottle effects": changes that occur when enclosing the plankton community that are often times unexplained by standard measures like pigment and nutrient concentrations. We noted variability in a short-term, nutrient amendment experiment during a 2019 Lake Erie, Microcystis spp. bloom. We observed changes in heterotrophic bacteria activity (transcription) on a time-frame consistent with a response to experimental changes in nutrient availability, demonstrating how the often overlooked microbiome of cyanobacterial blooms can be altered. Samples processed at the time of collection (T0) contained abundant transcripts from Bacteroidetes, which reduced in abundance during incubation in all bottles, including controls. Significant biological variability in the expression of Microcystis-infecting phage was observed between replicates, with phosphate-amended treatments showing a 10-fold variation. The expression patterns of Microcystis-infecting phage were significantly correlated with ∼35% of Microcystis-specific functional genes and ∼45% of the cellular-metabolites measured across the entire microbial community, suggesting phage activity not only influenced Microcystis dynamics, but the biochemistry of the microbiome. Our observations demonstrate how natural heterogeneity among replicates can be harnessed to provide further insight on virus and host ecology.
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Affiliation(s)
- Helena L Pound
- Department of Microbiology, The University of Tennessee, Knoxville, TN, United States
| | - Robbie M Martin
- Department of Microbiology, The University of Tennessee, Knoxville, TN, United States
| | - Brittany N Zepernick
- Department of Microbiology, The University of Tennessee, Knoxville, TN, United States
| | - Courtney J Christopher
- Biological and Small Molecule Mass Spectrometry Core, The University of Tennessee, Knoxville, TN, United States
| | - Sara M Howard
- Biological and Small Molecule Mass Spectrometry Core, The University of Tennessee, Knoxville, TN, United States
| | - Hector F Castro
- Biological and Small Molecule Mass Spectrometry Core, The University of Tennessee, Knoxville, TN, United States
| | - Shawn R Campagna
- Biological and Small Molecule Mass Spectrometry Core, The University of Tennessee, Knoxville, TN, United States
| | - Gregory L Boyer
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY, United States
| | - George S Bullerjahn
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States
| | - Justin D Chaffin
- Stone Laboratory and Ohio Sea Grant, The Ohio State University, Put-In-Bay, OH, United States
| | - Steven W Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, TN, United States
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9
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Pound HL, Gann ER, Wilhelm SW. A comparative study of metatranscriptomic assessment methods to characterize Microcystis blooms. LIMNOLOGY AND OCEANOGRAPHY, METHODS 2021; 19:846-854. [PMID: 35528780 PMCID: PMC9075346 DOI: 10.1002/lom3.10465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/28/2021] [Accepted: 10/19/2021] [Indexed: 06/14/2023]
Abstract
Harmful algal blooms are increasing in duration and severity globally, resulting in increased research interest. The use of genetic sequencing technologies has provided a wealth of opportunity to advance knowledge, but also poses a risk to that knowledge if handled incorrectly. The vast numbers of sequence processing tools and protocols provide a method to test nearly every hypothesis, but each method has inherent strengths and weaknesses. Here, we tested six methods to classify and quantify metatranscriptomic activity from a harmful algal bloom dominated by Microcystis spp. Three online tools were evaluated (Kaiju, MG-RAST, and GhostKOALA) in addition to three local tools that included a command line BLASTx approach, recruitment of reads to individual Microcystis genomes, and recruitment to a combined Microcystis composite genome generated from sequenced isolates with complete, closed genomes. Based on the analysis of each tool presented in this study, two recommendations are made that are dependent on the hypothesis to be tested. For researchers only interested in the function and physiology of Microcystis spp., read recruitments to the composite genome, referred to as "Frankenstein's Microcystis", provided the highest total estimates of transcript expression. However, for researchers interested in the entire bloom microbiome, the online GhostKOALA annotation tool, followed by subsequent read recruitments, provided functional and taxonomic characterization, in addition to transcript expression estimates. This study highlights the critical need for careful evaluation of methods before data analysis.
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Affiliation(s)
- Helena L. Pound
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Eric R. Gann
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Steven W. Wilhelm
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
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10
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Occurrence and diversity of viruses associated with cyanobacterial communities in a Brazilian freshwater reservoir. Braz J Microbiol 2021; 52:773-785. [PMID: 33791954 DOI: 10.1007/s42770-021-00473-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/25/2021] [Indexed: 02/06/2023] Open
Abstract
As part of the phytoplankton of marine and freshwater environments around the world, cyanobacteria interact with viruses (cyanophages) that affect their abundance and diversity. Investigations focusing on cyanophages co-occurring with freshwater cyanobacteria are scarce, particularly in Brazil. The aim of this study was to assess the diversity of cyanophages associated with a Microcystis-dominated cyanobacterial bloom in a tropical reservoir. Samples were processed as viral fractions of water and cellular fractions, and temporal fluctuations in the abundance of Ma-LMM01-type cyanophages and their Microcystis hosts were determined by qPCR. We applied shotgun metagenomics to obtain a wider characterization of the cyanophage community. During the study period, Microcystis gene copies were quantified in all cellular fractions, and the copy number of the Ma-LMM01 phage gene tended to increase with host abundance. Metagenomic analysis demonstrated that Caudovirales was the major viral order associated with the cyanophage families Myoviridae (34-88%), Podoviridae (3-42%), and Siphoviridae (6-23%). The metagenomic analysis results confirmed the presence of Microcystis cyanophages in both viral and cellular fractions and demonstrated a high relative abundance of picocyanobacteria-related viruses and Prochlorococcus (36-52%) and Synechococcus (37-50%) phages. For other main cyanobacterial genera, no related cyanophages were identified, which was probably due to the scarce representation of cyanophage sequences in databanks. Thus, the studied reservoir hosted a diverse cyanophage community with a remarkable contribution of phages related to picoplanktonic cyanobacteria. These results provide insights that motivate future sequencing efforts to assess cyanophage diversity and recover complete genomes.
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11
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Pound HL, Wilhelm SW. Tracing the active genetic diversity of Microcystis and Microcystis phage through a temporal survey of Taihu. PLoS One 2020; 15:e0244482. [PMID: 33370358 PMCID: PMC7769430 DOI: 10.1371/journal.pone.0244482] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/11/2020] [Indexed: 01/08/2023] Open
Abstract
Harmful algal blooms are commonly thought to be dominated by a single genus, but they are not homogenous communities. Current approaches, both molecular and culture-based, often overlook fine-scale variations in community composition that can influence bloom dynamics. We combined homology-based searches (BLASTX) and phylogenetics to distinguish and quantify Microcystis host and phage members across a summer season during a 2014 Microcystis- dominated bloom that occurred in Lake Tai (Taihu), China. We found 47 different genotypes of the Microcystis-specific DNA-dependent RNA polymerase (rpoB), which included several morphospecies. Microcystis flos-aquae and Microcystis wesenbergii accounted for ~86% of total Microcystis transcripts, while the more commonly studied Microcystis aeruginosa only accounted for ~7%. Microcystis genotypes were classified into three temporal groups according to their expression patterns across the course of the bloom: early, constant and late. All Microcystis morphospecies were present in each group, indicating that expression patterns were likely dictated by competition driven by environmental factors, not phylogeny. We identified three primary Microcystis-infecting phages based on the viral terminase, including a novel Siphoviridae phage that may be capable of lysogeny. Within our dataset, Myoviridae phages consistent with those infecting Microcystis in a lytic manner were positively correlated to the early host genotypes, while the Siphoviridae phages were positively correlated to the late host genotypes, when the Myoviridae phages express putative genetic markers for lysogeny. The expression of genes in the microcystin-encoding mcy cassette was estimated using mcyA, which revealed 24 Microcystis-specific genotypes that were negatively correlated to the early host genotypes. Of all environmental factors measured, pH best described the temporal shift in the Microcystis community genotypic composition, promoting hypotheses regarding carbon concentration mechanisms and oxidative stress. Our work expounds on the complexity of HAB events, using a well-studied dataset to highlight the need for increased resolution of community dynamics.
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Affiliation(s)
- Helena L. Pound
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, United States of America
| | - Steven W. Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee, United States of America
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12
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Roegner A, Sitoki L, Weirich C, Corman J, Owage D, Umami M, Odada E, Miruka J, Ogari Z, Smith W, Rejmankova E, Miller TR. Harmful Algal Blooms Threaten the Health of Peri-Urban Fisher Communities: A case study in Kisumu Bay, Lake Victoria, Kenya. EXPOSURE AND HEALTH 2020; 12:835-848. [PMID: 33748532 PMCID: PMC7968335 DOI: 10.1007/s12403-019-00342-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Available guidance to mitigate health risks from exposure to freshwater harmful algal blooms (HABs) is largely derived from temperate ecosystems. Yet in tropical ecosystems, HABs can occur year-round, and resource-dependent populations face multiple routes of exposure to toxic components. Along Winam Gulf, Lake Victoria, Kenya, fisher communities rely on lake water contaminated with microcystins (MCs) from HABs. In these peri-urban communities near Kisumu, we tested hypotheses that MCs exceed exposure guidelines across seasons, and persistent HABs present a chronic risk to fisher communities through ingestion with minimal water treatment and frequent, direct contact. We tested source waters at eleven communities across dry and rainy seasons from September 2015 through May 2016. We measured MCs, other metabolites, physicochemical parameters, chlorophyll a, phytoplankton abundance and diversity, and fecal indicators. We then selected four communities for interviews about water sources, usage, and treatment. Greater than 30% of source water samples exceeded WHO drinking water guidelines for MCs (1μg/L), and over 60% of source water samples exceeded USEPA guidelines for children and immunocompromised individuals. 50% of households reported sole use of raw lake water for drinking and household use, with alternate sources including rain and boreholes. Household chlorination was the most widespread treatment utilized. At this tropical, eutrophic lake, HABs pose a year-round health risk for fisher communities in resource -limited settings. Community-based solutions and site-specific guidance for Kisumu Bay and similarly impacted regions is needed to address a chronic health exposure likely to increase in severity and duration with global climate change.
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Affiliation(s)
- Amber Roegner
- Department of Environmental Science and Policy, University of California, Davis, CA, USA
- One Health Institute, School of Veterinary Medicine, University of California, Davis, CA, USA
- School of Natural Resources, University of Nebraska-Lincoln, NE, USA
| | - Lewis Sitoki
- Department of Earth and Environmental Sciences, Technical University of Kenya, Nairobi, Kenya
| | - Chelsea Weirich
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jessica Corman
- School of Natural Resources, University of Nebraska-Lincoln, NE, USA
| | - Dickson Owage
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - Moses Umami
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - Ephraim Odada
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - Jared Miruka
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - Zachary Ogari
- Kenya Marine and Fisheries Research Institute, Kisumu, Kenya
| | - Woutrina Smith
- One Health Institute, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - Eliska Rejmankova
- Department of Environmental Science and Policy, University of California, Davis, CA, USA
| | - Todd R Miller
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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13
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Morimoto D, Šulčius S, Yoshida T. Viruses of freshwater bloom-forming cyanobacteria: genomic features, infection strategies and coexistence with the host. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020; 12:486-502. [PMID: 32754956 DOI: 10.1111/1758-2229.12872] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/28/2020] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
Freshwater bloom-forming cyanobacteria densely grow in the aquatic environments, leading to an increase in the viral-contact rate. They possess numerous antiviral genes, as well as cell differentiation- and physiological performance-related genes, owing to genome expansion. Their genomic features and unique lifestyles suggest that they coexist with cyanoviruses in ways different from marine cyanobacteria. Furthermore, genome contents of isolated freshwater bloom-forming cyanobacterial viruses have little in common with those of marine cyanoviruses studied to date. They lack the marine cyanoviral hallmark genes that sustain photosynthetic activity and redirect host metabolism to viral reproduction; therefore, they are predicted to share metabolisms and precursor pools with host cyanobacteria to ensure efficient viral reproduction and avoid nutrient deficiencies and antiviral response. Additionally, cyanovirus-cyanobacteria coexistence strategies may change as bloom density increases. Diverse genotypic populations of cyanoviruses and hosts coexist and fluctuate under high viral-contact rate conditions, leading to their rapid coevolution through antiviral responses. The ancestral and newly evolved genotypes coexist, thereby expanding the diversity levels of host and viral populations. Bottleneck events occurring due to season-related decreases in bloom-forming species abundance provide each genotype within cyanobacterial population an equal chance to increase in prevalence during the next bloom and enhance further diversification.
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Affiliation(s)
- Daichi Morimoto
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Sigitas Šulčius
- Laboratory of Algology and Microbial Ecology, Nature Research Centre, Akademijos 2, Vilnius, 08412, Lithuania
| | - Takashi Yoshida
- Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto, 606-8502, Japan
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Expanding the Diversity of Bacterioplankton Isolates and Modeling Isolation Efficacy with Large-Scale Dilution-to-Extinction Cultivation. Appl Environ Microbiol 2020; 86:AEM.00943-20. [PMID: 32561583 PMCID: PMC7440811 DOI: 10.1128/aem.00943-20] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/13/2020] [Indexed: 12/13/2022] Open
Abstract
Even before the coining of the term “great plate count anomaly” in the 1980s, scientists had noted the discrepancy between the number of microorganisms observed under the microscope and the number of colonies that grew on traditional agar media. New cultivation approaches have reduced this disparity, resulting in the isolation of some of the “most wanted” bacterial lineages. Nevertheless, the vast majority of microorganisms remain uncultured, hampering progress toward answering fundamental biological questions about many important microorganisms. Furthermore, few studies have evaluated the underlying factors influencing cultivation success, limiting our ability to improve cultivation efficacy. Our work details the use of dilution-to-extinction (DTE) cultivation to expand the phylogenetic and geographic diversity of available axenic cultures. We also provide a new model of the DTE approach that uses cultivation results and natural abundance information to predict taxon-specific viability and iteratively constrain DTE experimental design to improve cultivation success. Cultivated bacterioplankton representatives from diverse lineages and locations are essential for microbiology, but the large majority of taxa either remain uncultivated or lack isolates from diverse geographic locales. We paired large-scale dilution-to-extinction (DTE) cultivation with microbial community analysis and modeling to expand the phylogenetic and geographic diversity of cultivated bacterioplankton and to evaluate DTE cultivation success. Here, we report results from 17 DTE experiments totaling 7,820 individual incubations over 3 years, yielding 328 repeatably transferable isolates. Comparison of isolates to microbial community data for source waters indicated that we successfully isolated 5% of the observed bacterioplankton community throughout the study; 43% and 26% of our isolates matched operational taxonomic units and amplicon single-nucleotide variants, respectively, within the top 50 most abundant taxa. Isolates included those from previously uncultivated clades such as SAR11 LD12 and Actinobacteria acIV, as well as geographically novel members from other ecologically important groups like SAR11 subclade IIIa, SAR116, and others, providing isolates in eight putatively new genera and seven putatively new species. Using a newly developed DTE cultivation model, we evaluated taxon viability by comparing relative abundance with cultivation success. The model (i) revealed the minimum attempts required for successful isolation of taxa amenable to growth on our media and (ii) identified possible subpopulation viability variation in abundant taxa such as SAR11 that likely impacts cultivation success. By incorporating viability in experimental design, we can now statistically constrain the effort necessary for successful cultivation of specific taxa on a defined medium. IMPORTANCE Even before the coining of the term “great plate count anomaly” in the 1980s, scientists had noted the discrepancy between the number of microorganisms observed under the microscope and the number of colonies that grew on traditional agar media. New cultivation approaches have reduced this disparity, resulting in the isolation of some of the “most wanted” bacterial lineages. Nevertheless, the vast majority of microorganisms remain uncultured, hampering progress toward answering fundamental biological questions about many important microorganisms. Furthermore, few studies have evaluated the underlying factors influencing cultivation success, limiting our ability to improve cultivation efficacy. Our work details the use of dilution-to-extinction (DTE) cultivation to expand the phylogenetic and geographic diversity of available axenic cultures. We also provide a new model of the DTE approach that uses cultivation results and natural abundance information to predict taxon-specific viability and iteratively constrain DTE experimental design to improve cultivation success.
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15
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Pound HL, Gann ER, Tang X, Krausfeldt LE, Huff M, Staton ME, Talmy D, Wilhelm SW. The "Neglected Viruses" of Taihu: Abundant Transcripts for Viruses Infecting Eukaryotes and Their Potential Role in Phytoplankton Succession. Front Microbiol 2020; 11:338. [PMID: 32210938 PMCID: PMC7067694 DOI: 10.3389/fmicb.2020.00338] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/17/2020] [Indexed: 01/18/2023] Open
Abstract
Drivers of algal bloom dynamics remain poorly understood, but viruses have been implicated as important players. Research addressing bloom dynamics has generally been restricted to the virus-infection of the numerically dominant (i.e. bloom forming) taxa. Yet this approach neglects a broad diversity of viral groups, limiting our knowledge of viral interactions and constraints within these systems. We examined hallmark virus marker genes in metatranscriptomic libraries from a seasonal and spatial survey of a Microcystis aeruginosa bloom in Lake Tai (Taihu) China to identify active infections by nucleocytoplasmic large DNA viruses (NCLDVs), RNA viruses, ssDNA viruses, bacteriophage, and virophage. Phylogenetic analyses revealed a diverse virus population with seasonal and spatial variability. We observed disproportionately high expression of markers associated with NCLDVs and ssRNA viruses (consistent with viruses that infect photosynthetic protists) relative to bacteriophage infecting heterotrophic bacteria or cyanobacteria during the height of the Microcystis bloom event. Under a modified kill-the-winner scheme, we hypothesize viruses infecting protists help suppress the photosynthetic eukaryotic community and allow for the proliferation of cyanobacteria such as Microcystis. Our observations provide a foundation for a little considered factor promoting algal blooms.
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Affiliation(s)
- Helena L Pound
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Eric R Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Xiangming Tang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China
| | - Lauren E Krausfeldt
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Matthew Huff
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Margaret E Staton
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - David Talmy
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Steven W Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
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16
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Krausfeldt LE, Steffen MM, McKay RM, Bullerjahn GS, Boyer GL, Wilhelm SW. Insight Into the Molecular Mechanisms for Microcystin Biodegradation in Lake Erie and Lake Taihu. Front Microbiol 2019; 10:2741. [PMID: 31921001 PMCID: PMC6914704 DOI: 10.3389/fmicb.2019.02741] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/11/2019] [Indexed: 01/04/2023] Open
Abstract
Microcystins are potent hepatotoxins that are frequently detected in fresh water lakes plagued by toxic cyanobacteria. Microbial biodegradation has been referred to as the most important avenue for removal of microcystin from aquatic environments. The biochemical pathway most commonly associated with the degradation of microcystin is encoded by the mlrABCD (mlr) cassette. The ecological significance of this pathway remains unclear as no studies have examined the expression of these genes in natural environments. Six metatranscriptomes were generated from microcystin-producing Microcystis blooms and analyzed to assess the activity of this pathway in environmental samples. Seventy-eight samples were collected from Lake Erie, United States/Canada and Lake Tai (Taihu), China, and screened for the presence of mlr gene transcripts. Read mapping to the mlr cassette indicated transcripts for these genes were absent, with only 77 of the collective 3.7 billion reads mapping to any part of the mlr cassette. Analysis of the assembled metatranscriptomes supported this, with only distantly related sequences identified as mlrABC-like. These observations were made despite the presence of microcystin and over 500,000 reads mapping to the mcy cassette for microcystin production. Glutathione S-transferases and alkaline proteases have been previously hypothesized to be alternative pathways for microcystin biodegradation, and expression of these genes was detected across space and time in both lakes. While the activity of these alternative pathways needs to be experimentally confirmed, they may be individually or collectively more important than mlr genes in the natural environment. Importantly, the lack of mlr expression could indicate microcystin biodegradation was not occurring in the analyzed samples. This study raises interesting questions about the ubiquity, specificity and locality of microcystin biodegradation, and highlights the need for the characterization of relevant mechanisms in natural communities to understand the fate of microcystin in the environment and risk to public health.
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Affiliation(s)
- Lauren E. Krausfeldt
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Morgan M. Steffen
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Robert M. McKay
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
| | - George S. Bullerjahn
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, United States
| | - Gregory L. Boyer
- Department of Chemistry, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, United States
| | - Steven W. Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
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17
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Cooccurrence of Broad- and Narrow-Host-Range Viruses Infecting the Bloom-Forming Toxic Cyanobacterium Microcystis aeruginosa. Appl Environ Microbiol 2019; 85:AEM.01170-19. [PMID: 31324627 DOI: 10.1128/aem.01170-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 07/11/2019] [Indexed: 12/20/2022] Open
Abstract
Viruses play important roles in regulating the abundance and composition of bacterial populations in aquatic ecosystems. The bloom-forming toxic cyanobacterium Microcystis aeruginosa is predicted to interact with diverse cyanoviruses, resulting in Microcystis population diversification. However, current knowledge of the genomes from these viruses and their infection programs is limited to those of Microcystis virus Ma-LMM01. Here, we performed a time series sampling at a small pond in Japan during a Microcystis bloom and then investigated the genomic information and transcriptional dynamics of Microcystis-interacting viruses using metagenomic and metatranscriptomic approaches. We identified 15 viral genomic fragments classified into three groups, groups I (including Ma-LMM01), II (high abundance and transcriptional activity), and III (new lineages). According to the phylogenetic distribution of Microcystis strains possessing spacers against each viral group, the group II-original viruses interacted with all three phylogenetically distinct Microcystis population types (phylotypes), whereas the groups I and III-original viruses interacted with only one or two phylotypes, indicating the cooccurrence of broad- (group II) and narrow (groups I and III)-host-range viruses in the bloom. These viral fragments showed the highest transcriptional levels during daytime regardless of their genomic differences. Interestingly, M. aeruginosa expressed antiviral defense genes in the environment, unlike what was seen with an Ma-LMM01 infection in a previous culture experiment. Given that broad-host-range viruses often induce antiviral responses within alternative hosts, our findings suggest that such antiviral responses might inhibit viral multiplication, mainly that of broad-host-range viruses like those in group II.IMPORTANCE The bloom-forming toxic cyanobacterium Microcystis aeruginosa is thought to have diversified its population through the interactions between host and viruses in antiviral defense systems. However, current knowledge of viral genomes and infection programs is limited to those of Microcystis virus Ma-LMM01, which was a narrow host range in which it can escape from the highly abundant host defense systems. Our metagenomic approaches unveiled the cooccurrence of narrow- and broad-host-range Microcystis viruses, which included fifteen viral genomic fragments from Microcystis blooms that were classified into three groups. Interestingly, Microcystis antiviral defense genes were expressed against viral infection in the environment, unlike what was seen in a culture experiment with Ma-LMM01. Given that viruses with a broad host range often induce antiviral responses within alternative hosts, our findings suggest that antiviral responses inhibit viral reproduction, especially that of broad-range viruses like those in group II. This paper augments our understanding of the interactions between M. aeruginosa and its viruses and fills an important knowledge gap.
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18
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Wang J, Bai P, Li Q, Lin Y, Huo D, Ke F, Zhang Q, Li T, Zhao J. Interaction between cyanophage MaMV-DC and eight Microcystis strains, revealed by genetic defense systems. HARMFUL ALGAE 2019; 85:101699. [PMID: 31810530 DOI: 10.1016/j.hal.2019.101699] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
Cyanophage MaMV-DC is a member of Myoviridae that was reported to specifically infect and lyse Microcystis aeruginosa FACHB-524 among 21 selected cyanobacterial strains. We reidentified the infection specificity of MaMV-DC among seven other Microcystis strains of different species. In our experiments, MaMV-DC infected three Microcystis strains but did not form plaque in Microcystis lawns. This indicated that MaMV-DC is at least a genus- rather than strain-specific virus. Cyanophage MaMV-DC genes were transcribed in M. aeruginosa FACHB-524, M. flos-aquae TF09, M. aeruginosa TA09 and M. wesenbergii DW09, and the growth of these Microcystis strains was inhibited by the addition of MaMV-DC. The predicted defense of eight Microcystis strains by CRISPR-Cas systems has shown mixed consistency with the infection experiment results, suggesting other defense or anti-defense systems play roles during infection process. Restriction-modification (RM) system analysis revealed an abundance of four types of RM proteins that may play roles in defense against cyanophages.
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Affiliation(s)
- Juanping Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Zhongnan Hospital, Wuhan University, Wuhan 430071, China
| | - Peng Bai
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Yan Lin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Da Huo
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fei Ke
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Qiya Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Tao Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Jindong Zhao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
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19
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Stough JMA, Yutin N, Chaban YV, Moniruzzaman M, Gann ER, Pound HL, Steffen MM, Black JN, Koonin EV, Wilhelm SW, Short SM. Genome and Environmental Activity of a Chrysochromulina parva Virus and Its Virophages. Front Microbiol 2019; 10:703. [PMID: 31024489 PMCID: PMC6459981 DOI: 10.3389/fmicb.2019.00703] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 03/20/2019] [Indexed: 01/06/2023] Open
Abstract
Some giant viruses are ecological agents that are predicted to be involved in the top-down control of single-celled eukaryotic algae populations in aquatic ecosystems. Despite an increased interest in giant viruses since the discovery and characterization of Mimivirus and other viral giants, little is known about their physiology and ecology. In this study, we characterized the genome and functional potential of a giant virus that infects the freshwater haptophyte Chrysochromulina parva, originally isolated from Lake Ontario. This virus, CpV-BQ2, is a member of the nucleo-cytoplasmic large DNA virus (NCLDV) group and possesses a 437 kb genome encoding 503 ORFs with a GC content of 25%. Phylogenetic analyses of core NCLDV genes place CpV-BQ2 amongst the emerging group of algae-infecting Mimiviruses informally referred to as the “extended Mimiviridae,” making it the first virus of this group to be isolated from a freshwater ecosystem. During genome analyses, we also captured and described the genomes of three distinct virophages that co-occurred with CpV-BQ2 and likely exploit CpV for their own replication. These virophages belong to the polinton-like viruses (PLV) group and encompass 19–23 predicted genes, including all of the core PLV genes as well as several genes implicated in genome modifications. We used the CpV-BQ2 and virophage reference sequences to recruit reads from available environmental metatranscriptomic data to estimate their activity in fresh waters. We observed moderate recruitment of both virus and virophage transcripts in samples obtained during Microcystis aeruginosa blooms in Lake Erie and Lake Tai, China in 2013, with a spike in activity in one sample. Virophage transcript abundance for two of the three isolates strongly correlated with that of the CpV-BQ2. Together, the results highlight the importance of giant viruses in the environment and establish a foundation for future research on the physiology and ecology CpV-BQ2 as a model system for algal Mimivirus dynamics in freshwaters.
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Affiliation(s)
- Joshua M A Stough
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States
| | - Yuri V Chaban
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Mohammed Moniruzzaman
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Eric R Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Helena L Pound
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Morgan M Steffen
- Department of Biology, James Madison University, Harrisonburg, VA, United States
| | - Jenna N Black
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States
| | - Steven W Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Steven M Short
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
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20
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Martin RM, Moniruzzaman M, Mucci NC, Willis A, Woodhouse JN, Xian Y, Xiao C, Brussaard CPD, Wilhelm SW. Cylindrospermopsis raciborskii Virus and host: genomic characterization and ecological relevance. Environ Microbiol 2018; 21:1942-1956. [PMID: 30251319 DOI: 10.1111/1462-2920.14425] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 01/21/2023]
Abstract
Cylindrospermopsis (Raphidiopsis) raciborskii is an invasive, filamentous, nitrogen-fixing cyanobacterium that forms frequent blooms in freshwater habitats. While viruses play key roles in regulating the abundance, production and diversity of their hosts in aquatic ecosystems, the role(s) of viruses in the ecology of C. raciborskii is almost unexplored. Progress in this field has been hindered by the absence of a characterized virus-host system in C. raciborskii. To bridge this gap, we sequenced the genome of CrV-01T, a previously isolated cyanosiphovirus, and its host, C. raciborskii strain Cr2010. Analyses suggest that CrV-01T represents a distinct clade of siphoviruses infecting, and perhaps lysogenizing, filamentous cyanobacteria. Its genome contains unique features that include an intact CRISPR array and a 12 kb inverted duplication. Evidence suggests CrV-01T recently gained the ability to infect Cr2010 and recently lost the ability to form lysogens. The cyanobacterial host contains a CRISPR-Cas system with CRISPR spacers matching protospacers within the inverted duplication of the CrV-01T genome. Examination of metagenomes demonstrates that viruses with high genetic identity to CrV-01T, but lacking the inverted duplication, are present in C. raciborskii blooms in Australia. The unique genomic features of the CrV/Cr2010 system offers opportunities to investigate in more detail virus-host interactions in an ecologically important bloom-forming cyanobacterium.
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Affiliation(s)
- Robbie M Martin
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA
| | | | - Nicholas C Mucci
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA
| | - Anusuya Willis
- Australian National Algae Culture Collection, CSIRO National Collections and Marine Infrastructure, Hobart, Australia
| | - Jason N Woodhouse
- Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Yuejiao Xian
- Department of Chemistry, University of Texas at El Paso, El Paso, TX, USA
| | - Chuan Xiao
- Department of Chemistry, University of Texas at El Paso, El Paso, TX, USA
| | - Corina P D Brussaard
- Department of Marine Microbiology and Biogeochemistry, and Utrecht University, Royal Netherlands Institute for Sea Research, Texel, The Netherlands
| | - Steven W Wilhelm
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA
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21
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Tang X, Krausfeldt LE, Shao K, LeCleir GR, Stough JMA, Gao G, Boyer GL, Zhang Y, Paerl HW, Qin B, Wilhelm SW. Seasonal Gene Expression and the Ecophysiological Implications of Toxic Microcystis aeruginosa Blooms in Lake Taihu. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11049-11059. [PMID: 30168717 DOI: 10.1021/acs.est.8b01066] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Harmful cyanobacterial blooms represent an increasing threat to freshwater resources globally. Despite increased research, the physiological basis of how the dominant bloom-forming cyanobacteria, Microcystis spp., proliferate and then maintain high population densities through changing environmental conditions is poorly understood. In this study, we examined the transcriptional profiles of the microbial community in Lake Taihu, China at 9 stations sampled monthly from June to October in 2014. To target Microcystis populations, we collected metatranscriptomic data and mapped reads to the M. aeruginosa NIES 843 genome. Our results revealed significant temporal gene expression patterns, with many genes separating into either early or late bloom clusters. About one-third of genes observed from M. aeruginosa were differentially expressed between these two clusters. Conductivity and nutrient availability appeared to be the environmental factors most strongly associated with these temporal gene expression shifts. Compared with the early bloom season (June and July), genes involved in N and P transport, energy metabolism, translation, and amino acid biosynthesis were down-regulated during the later season (August to October). In parallel, genes involved in regulatory functions as well as transposases and the production of microcystin and extracellular polysaccharides were up-regulated in the later season. Our observation indicates an eco-physiological shift occurs within the Microcystis spp. transcriptome as cells move from the rapid growth of early summer to bloom maintenance in late summer and autumn.
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Affiliation(s)
- Xiangming Tang
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China
| | - Lauren E Krausfeldt
- Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Keqiang Shao
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China
| | - Gary R LeCleir
- Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Joshua M A Stough
- Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Guang Gao
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China
| | - Gregory L Boyer
- Department of Chemistry , SUNY College of Environmental Science and Forestry , Syracuse , New York 13210 , United States
| | - Yunlin Zhang
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China
| | - Hans W Paerl
- Institute of Marine Sciences , The University of North Carolina at Chapel Hill , Morehead City , North Carolina 28557 , United States
- College of Environment , Hohai University , Nanjing , Jiangsu 210098 , China
| | - Boqiang Qin
- Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment , Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing , Jiangsu 210008 , China
| | - Steven W Wilhelm
- Department of Microbiology , University of Tennessee , Knoxville , Tennessee 37996 , United States
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