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Yancey CE, Smith DJ, Den Uyl PA, Mohamed OG, Yu F, Ruberg SA, Chaffin JD, Goodwin KD, Tripathi A, Sherman DH, Dick GJ. Metagenomic and Metatranscriptomic Insights into Population Diversity of Microcystis Blooms: Spatial and Temporal Dynamics of mcy Genotypes, Including a Partial Operon That Can Be Abundant and Expressed. Appl Environ Microbiol 2022; 88:e0246421. [PMID: 35438519 PMCID: PMC9088275 DOI: 10.1128/aem.02464-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/14/2022] [Indexed: 11/29/2022] Open
Abstract
Cyanobacterial harmful algal blooms (cyanoHABs) degrade freshwater ecosystems globally. Microcystis aeruginosa often dominates cyanoHABs and produces microcystin (MC), a class of hepatotoxins that poses threats to human and animal health. Microcystin toxicity is influenced by distinct structural elements across a diversity of related molecules encoded by variant mcy operons. However, the composition and distribution of mcy operon variants in natural blooms remain poorly understood. Here, we characterized the variant composition of mcy genes in western Lake Erie Microcystis blooms from 2014 and 2018. Sampling was conducted across several spatial and temporal scales, including different bloom phases within 2014, extensive spatial coverage on the same day (2018), and frequent, autonomous sampling over a 2-week period (2018). Mapping of metagenomic and metatranscriptomic sequences to reference sequences revealed three Microcystis mcy genotypes: complete (all genes present [mcyA-J]), partial (truncated mcyA, complete mcyBC, and missing mcyD-J), and absent (no mcy genes). We also detected two different variants of mcyB that may influence the production of microcystin congeners. The relative abundance of these genotypes was correlated with pH and nitrate concentrations. Metatranscriptomic analysis revealed that partial operons were, at times, the most abundant genotype and expressed in situ, suggesting the potential biosynthesis of truncated products. Quantification of genetic divergence between genotypes suggests that the observed strains are the result of preexisting heterogeneity rather than de novo mutation during the sampling period. Overall, our results show that natural Microcystis populations contain several cooccurring mcy genotypes that dynamically shift in abundance spatiotemporally via strain succession and likely influence the observed diversity of the produced congeners. IMPORTANCE Cyanobacteria are responsible for producing microcystins (MCs), a class of potent and structurally diverse toxins, in freshwater systems around the world. While microcystins have been studied for over 50 years, the diversity of their chemical forms and how this variation is encoded at the genetic level remain poorly understood, especially within natural populations of cyanobacterial harmful algal blooms (cyanoHABs). Here, we leverage community DNA and RNA sequences to track shifts in mcy genes responsible for producing microcystin, uncovering the relative abundance, expression, and variation of these genes. We studied this phenomenon in western Lake Erie, which suffers annually from cyanoHAB events, with impacts on drinking water, recreation, tourism, and commercial fishing.
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Affiliation(s)
- Colleen E. Yancey
- Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Derek J. Smith
- Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Paul A. Den Uyl
- Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan, Ann Arbor, Michigan, USA
| | - Osama G. Mohamed
- Natural Products Discovery Core, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
- Life Science Institute, University of Michigan, Ann Arbor, Michigan, USA
- Pharmacognosy Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Fengan Yu
- Life Science Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Steven A. Ruberg
- National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory, Ann Arbor, Michigan, USA
| | - Justin D. Chaffin
- F. T. Stone Laboratory, The Ohio State University, Put-In-Bay, Ohio, USA
- Ohio Sea Grant, The Ohio State University, Put-In-Bay, Ohio, USA
| | - Kelly D. Goodwin
- Ocean Chemistry and Ecosystems Division, Atlantic Oceanographic and Meteorological Laboratory (AOML), NOAA, Miami, Florida, USA
- Southwest Fisheries Science Center, NOAA, La Jolla, California, USA
| | - Ashootosh Tripathi
- Natural Products Discovery Core, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
- Life Science Institute, University of Michigan, Ann Arbor, Michigan, USA
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - David H. Sherman
- Life Science Institute, University of Michigan, Ann Arbor, Michigan, USA
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Gregory J. Dick
- Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
- Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan, Ann Arbor, Michigan, USA
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Bouma-Gregson K, Crits-Christoph A, Olm MR, Power ME, Banfield JF. Microcoleus (Cyanobacteria) form watershed-wide populations without strong gradients in population structure. Mol Ecol 2021; 31:86-103. [PMID: 34608694 PMCID: PMC9298114 DOI: 10.1111/mec.16208] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 11/28/2022]
Abstract
The relative importance of separation by distance and by environment to population genetic diversity can be conveniently tested in river networks, where these two drivers are often independently distributed over space. To evaluate the importance of dispersal and environmental conditions in shaping microbial population structures, we performed genome‐resolved metagenomic analyses of benthic Microcoleus‐dominated cyanobacterial mats collected in the Eel and Russian River networks (California, USA). The 64 Microcoleus genomes were clustered into three species that shared >96.5% average nucleotide identity (ANI). Most mats were dominated by one strain, but minor alleles within mats were often shared, even over large spatial distances (>300 km). Within the most common Microcoleus species, the ANI between the dominant strains within mats decreased with increasing spatial separation. However, over shorter spatial distances (tens of kilometres), mats from different subwatersheds had lower ANI than mats from the same subwatershed, suggesting that at shorter spatial distances environmental differences between subwatersheds in factors like canopy cover, conductivity, and mean annual temperature decreases ANI. Since mats in smaller creeks had similar levels of nucleotide diversity (π) as mats in larger downstream subwatersheds, within‐mat genetic diversity does not appear to depend on the downstream accumulation of upstream‐derived strains. The four‐gamete test and sequence length bias suggest recombination occurs between almost all strains within each species, even between populations separated by large distances or living in different habitats. Overall, our results show that, despite some isolation by distance and environmental conditions, sufficient gene‐flow occurs among cyanobacterial strains to prevent either driver from producing distinctive population structures across the watershed.
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Affiliation(s)
- Keith Bouma-Gregson
- Office of Information Management and Analysis, State Water Resources Control Board, Sacramento, California, USA.,Earth and Planetary Science Department, University of California, Berkeley, California, USA
| | | | - Mathew R Olm
- Plant and Microbial Ecology Department, University of California, Berkeley, California, USA
| | - Mary E Power
- Integrative Biology Department, University of California, Berkeley, California, USA
| | - Jillian F Banfield
- Earth and Planetary Science Department, University of California, Berkeley, California, USA.,Plant and Microbial Ecology Department, University of California, Berkeley, California, USA.,Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.,Chan Zuckerberg Biohub, San Francisco, California, USA
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Arning N, Wilson DJ. The past, present and future of ancient bacterial DNA. Microb Genom 2020; 6:mgen000384. [PMID: 32598277 PMCID: PMC7478633 DOI: 10.1099/mgen.0.000384] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022] Open
Abstract
Groundbreaking studies conducted in the mid-1980s demonstrated the possibility of sequencing ancient DNA (aDNA), which has allowed us to answer fundamental questions about the human past. Microbiologists were thus given a powerful tool to glimpse directly into inscrutable bacterial history, hitherto inaccessible due to a poor fossil record. Initially plagued by concerns regarding contamination, the field has grown alongside technical progress, with the advent of high-throughput sequencing being a breakthrough in sequence output and authentication. Albeit burdened with challenges unique to the analysis of bacteria, a growing number of viable sources for aDNA has opened multiple avenues of microbial research. Ancient pathogens have been extracted from bones, dental pulp, mummies and historical medical specimens and have answered focal historical questions such as identifying the aetiological agent of the black death as Yersinia pestis. Furthermore, ancient human microbiomes from fossilized faeces, mummies and dental plaque have shown shifts in human commensals through the Neolithic demographic transition and industrial revolution, whereas environmental isolates stemming from permafrost samples have revealed signs of ancient antimicrobial resistance. Culminating in an ever-growing repertoire of ancient genomes, the quickly expanding body of bacterial aDNA studies has also enabled comparisons of ancient genomes to their extant counterparts, illuminating the evolutionary history of bacteria. In this review we summarize the present avenues of research and contextualize them in the past of the field whilst also pointing towards questions still to be answered.
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Affiliation(s)
- Nicolas Arning
- Big Data Institute, Nuffield Department of Population Health, University of Oxford, Li Ka Shing Centre for Health Information and Discovery, Old Road Campus, Oxford, OX3 7LF, UK
| | - Daniel J. Wilson
- Big Data Institute, Nuffield Department of Population Health, University of Oxford, Li Ka Shing Centre for Health Information and Discovery, Old Road Campus, Oxford, OX3 7LF, UK
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Segawa T, Yonezawa T. Evaluation of reported sediment samples from 20 Ma using a molecular phylogenetic approach: comment on Liu et al. (2017). Environ Microbiol 2020; 22:813-818. [PMID: 31984637 DOI: 10.1111/1462-2920.14923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/23/2019] [Accepted: 01/22/2020] [Indexed: 11/28/2022]
Abstract
Liu et al. reported the cultivation and DNA sequencing of 69 fungal isolates (Ascomycota and Basidiomycota) from ancient subseafloor sediments, suggesting that they represent living fungal populations that have persisted for over 20 million years. Because these findings could bring about a paradigm shift in our understanding of the spatial breadth of the deep subsurface biosphere as well as the longevity of ancient DNA, it is extremely important to verify that their samples represent pure ancient fungi from 20 million years ago without contamination by modern species. For this purpose, we estimated the divergence times of Dikarya (Ascomycota + Basidiomycota) and Mucoromycota fungi assuming that the fungal isolates were actually sampled from 20 Ma (mega-annum) sediments and evaluated the validity of the sample ages. Using this approach, we estimate that the age of the last common ancestor of Dikarya and Mucoromycota fungi greatly exceeds the age of the Earth. Our finding emphasizes the importance of using reliable approaches to confirm the dating of ancient samples.
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Affiliation(s)
- Takahiro Segawa
- Center for Life Science Research, University of Yamanashi, 1110, Shimokato, Chuo, Yamanashi, Japan
| | - Takahiro Yonezawa
- Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737, Funako, Atsugi, Kanagawa, Japan
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Salmaso N. Effects of Habitat Partitioning on the Distribution of Bacterioplankton in Deep Lakes. Front Microbiol 2019; 10:2257. [PMID: 31636614 PMCID: PMC6788347 DOI: 10.3389/fmicb.2019.02257] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/17/2019] [Indexed: 12/04/2022] Open
Abstract
In deep lakes, many investigations highlighted the existence of exclusive groups of bacteria adapted to deep oxygenated and hypoxic and anoxic hypolimnia. Nevertheless, the extent of bacterial strain diversity has been much less scrutinized. This aspect is essential for an unbiased estimation of genetic variation, biodiversity, and population structure, which are essential for studying important research questions such as biogeographical patterns, temporal and spatial variability and the environmental factors affecting this variability. This study investigated the bacterioplankton community in the epilimnetic layers and in the oxygenated and hypoxic/anoxic hypolimnia of five large and deep lakes located at the southern border of the Alps using high throughput sequencing (HTS) analyses (16S rDNA) and identification of amplicon sequence variants (ASVs) resolving reads differing by as little as one nucleotide. The study sites, which included two oligomictic (Garda and Como) and three meromictic lakes (Iseo, Lugano, and Idro) with maximum depths spanning from 124 to 410 m, were chosen among large lakes to represent an oxic-hypoxic gradient. The analyses showed the existence of several unique ASVs in the three layers of the five lakes. In the case of cyanobacteria, this confirmed previous analyses made at the level of strains or based on oligotyping methods. As expected, the communities in the hypoxic/anoxic monimolimnia showed a strong differentiation from the oxygenated layer, with the exclusive presence in single lakes of several unique ASVs. In the meromictic lakes, results supported the hypothesis that the formation of isolated monimolimnia sustained the development of highly diversified bacterial communities through ecological selection, leading to the establishment of distinctive biodiversity zones. The genera identified in these layers are well-known to activate a wide range of redox reactions at low O2 conditions. As inferred from 16S rDNA data, the highly diversified and coupled processes sustained by the monimolimnetic microbiota are essential ecosystem services that enhance mineralization of organic matter and formation of reduced compounds, and also abatement of undesirable greenhouse gasses.
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Affiliation(s)
- Nico Salmaso
- Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
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Zawierucha K, Shain DH. Disappearing Kilimanjaro snow-Are we the last generation to explore equatorial glacier biodiversity? Ecol Evol 2019; 9:8911-8918. [PMID: 31410289 PMCID: PMC6686285 DOI: 10.1002/ece3.5327] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/11/2019] [Accepted: 05/18/2019] [Indexed: 11/29/2022] Open
Abstract
Glaciation accompanied our human ancestors in Africa throughout the Pleistocene. Regrettably, equatorial glaciers and snow are disappearing rapidly, and we are likely the last generation who will get to know these peculiar places. Despite the permanently harsh conditions of glacier/snow habitats, they support a remarkable diversity of life ranging from bacteria to animals. Numerous papers have been devoted to microbial communities and unique animals on polar glaciers and high mountains, but only two reports relate to glacial biodiversity in equatorial regions, which are destined to melt completely within the next few decades. Equatorial glaciers constitute "cold islands" in tropics, and discovering their diversity might shed light on the biogeography, dispersal, and history of psychrophiles. Thus, an opportunity to protect biota of equatorial glaciers hinges on ex situ conservation. It is timely and crucial that we should investigate the glacial biodiversity of the few remaining equatorial glaciers.
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Affiliation(s)
- Krzysztof Zawierucha
- Department of Animal Taxonomy and Ecology, Faculty of BiologyAdam Mickiewicz UniversityPoznańPoland
| | - Daniel H. Shain
- Biology DepartmentRutgers, The State University of New JerseyCamdenNew Jersey
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Łokas E, Zawierucha K, Cwanek A, Szufa K, Gaca P, Mietelski JW, Tomankiewicz E. The sources of high airborne radioactivity in cryoconite holes from the Caucasus (Georgia). Sci Rep 2018; 8:10802. [PMID: 30018384 PMCID: PMC6050279 DOI: 10.1038/s41598-018-29076-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/02/2018] [Indexed: 11/12/2022] Open
Abstract
Cryoconite granules are mixtures of mineral particles, organic substances and organisms on the surface of glaciers where they decrease the ice albedo and are responsible for formation of water-filled holes. The contaminants are effectively trapped in the cryoconite granules and stay there for many years. This study evaluates the contamination level of artificial and natural radionuclides in cryoconite holes from Adishi glacier (Georgia) and identifies the sources of contamination based on activity or mass ratios among artificial radionuclides. Results revealed high activity concentrations of fallout radionuclides reaching 4900 Bq/kg, 2.5 Bq/kg, 107 Bq/kg and 68 Bq/kg for 137Cs, 238Pu, 239+240Pu and 241Am, respectively. The main source of Pu is global fallout, but the low 240Pu/239Pu atomic ratios also indicated local tropospheric source of 239Pu, probably from the Kapustin Yar nuclear test site. Also, high activity ratios of 241Am/239+240Pu could originate from Kapustin Yar. The natural radionuclides originate from the surrounding rocks and were measured to control the environmental processes. 210Pb in cryoconite granules comes predominantly from the atmospheric deposition, and its activity concentrations reach high values up to 12000 Bq/kg.
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Affiliation(s)
- Edyta Łokas
- Department of Nuclear Physical Chemistry, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Radzikowskiego 152, 31-342, Poland.
| | - Krzysztof Zawierucha
- Department of Animal Taxonomy and Ecology, Adam Mickiewicz University, Poznań, Poland
| | - Anna Cwanek
- Department of Nuclear Physical Chemistry, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Radzikowskiego 152, 31-342, Poland
| | - Katarzyna Szufa
- Department of Nuclear Physical Chemistry, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Radzikowskiego 152, 31-342, Poland
| | - Paweł Gaca
- GAU-Radioanalytical Laboratories, Ocean and Earth Science, University of Southampton, National Oceanography Centre, European Way, Southampton, United Kingdom
| | - Jerzy W Mietelski
- Department of Nuclear Physical Chemistry, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Radzikowskiego 152, 31-342, Poland
| | - Ewa Tomankiewicz
- Department of Nuclear Physical Chemistry, Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Radzikowskiego 152, 31-342, Poland
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