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Wang YL, Ikuma K, Brooks SC, Varonka MS, Deonarine A. Non-mercury methylating microbial taxa are integral to understanding links between mercury methylation and elemental cycles in marine and freshwater sediments. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123573. [PMID: 38365074 DOI: 10.1016/j.envpol.2024.123573] [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: 10/04/2023] [Revised: 01/09/2024] [Accepted: 02/13/2024] [Indexed: 02/18/2024]
Abstract
The goal of this study was to explore the role of non-mercury (Hg) methylating taxa in mercury methylation and to identify potential links between elemental cycles and Hg methylation. Statistical approaches were utilized to investigate the microbial community and biochemical functions in relation to methylmercury (MeHg) concentrations in marine and freshwater sediments. Sediments were collected from the methylation zone (top 15 cm) in four Hg-contaminated sites. Both abiotic (e.g., sulfate, sulfide, iron, salinity, total organic matter, etc.) and biotic factors (e.g., hgcA, abundances of methylating and non-methylating taxa) were quantified. Random forest and stepwise regression were performed to assess whether non-methylating taxa were significantly associated with MeHg concentration. Co-occurrence and functional network analyses were constructed to explore associations between taxa by examining microbial community structure, composition, and biochemical functions across sites. Regression analysis showed that approximately 80% of the variability in sediment MeHg concentration was predicted by total mercury concentration, the abundances of Hg methylating taxa, and the abundances of the non-Hg methylating taxa. The co-occurrence networks identified Paludibacteraceae and Syntrophorhabdaceae as keystone non Hg methylating taxa in multiple sites, indicating the potential for syntrophic interactions with Hg methylators. Strong associations were also observed between methanogens and sulfate-reducing bacteria, which were likely symbiotic associations. The functional network results suggested that non-Hg methylating taxa play important roles in sulfur respiration, nitrogen respiration, and the carbon metabolism-related functions methylotrophy, methanotrophy, and chemoheterotrophy. Interestingly, keystone functions varied by site and did not involve carbon- and sulfur-related functions only. Our findings highlight associations between methylating and non-methylating taxa and sulfur, carbon, and nitrogen cycles in sediment methylation zones, with implications for predicting and understanding the impact of climate and land/sea use changes on Hg methylation.
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Affiliation(s)
- Yong-Li Wang
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States
| | - Kaoru Ikuma
- Department of Civil, Construction & Environmental Engineering, Iowa State University, Ames, IA, United States
| | - Scott C Brooks
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States
| | - Matthew S Varonka
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, United States
| | - Amrika Deonarine
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States.
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Wang Y, Berthold DE, Hu J, Lefler FW, Huang IS, Laughinghouse HD. Novel diversity within Roseofilum (Desertifilaceae, Cyanobacteria) from marine benthic mats with description of four new species. JOURNAL OF PHYCOLOGY 2023; 59:1147-1165. [PMID: 37824435 DOI: 10.1111/jpy.13392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 08/09/2023] [Accepted: 09/07/2023] [Indexed: 10/14/2023]
Abstract
Benthic cyanobacterial mats (BCMs) are natural phenomena in marine environments. Reports of BCMs occurring across coastal marine environments have increased, partly driven by nutrient loading and climate change; thus, there is a need to understand the diversity involved in the proliferations and potential toxicity of the BCMs. Furthermore, marine cyanobacterial mats are observed growing on and affecting the health of corals with one specific cyanobacterial genus, Roseofilum, dominating the microbial mats associated with black band disease (BBD), a destructive polymicrobial disease that affects corals. To explore the diversity of Roseofilum, cyanobacterial mats from various marine habitats were sampled, and individual isolates were identified based on morphology, 16S rRNA gene phylogenies, 16S-23S ITS rRNA region sequence dissimilarities, and phylogenomics. Four novel species of Roseofilum were isolated from benthic marine mats, three from the coasts of Florida, United States (R. capinflatum sp. nov., R. casamattae sp. nov., and R. acuticapitatum sp. nov.) and one from the coast of France (R. halophilum sp. nov.). Our analyses revealed that Roseofilum associated with coral BBD and those not associated with corals but rather from coastal benthic mats are systematically distinct based on both phylogenetic and phylogenomic analyses. Enzyme-linked immunosorbent assay (ELISA) and LC-MS data indicated that microcystin production was found in one of the four species.
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Affiliation(s)
- Yi Wang
- Fort Lauderdale Research and Education Center, University of Florida - IFAS, Davie, Florida, USA
| | - David E Berthold
- Fort Lauderdale Research and Education Center, University of Florida - IFAS, Davie, Florida, USA
| | - Jing Hu
- Fort Lauderdale Research and Education Center, University of Florida - IFAS, Davie, Florida, USA
- Department of Marine Science, Ocean College, Zhejiang University, Zhoushan, People's Republic of China
| | - Forrest W Lefler
- Fort Lauderdale Research and Education Center, University of Florida - IFAS, Davie, Florida, USA
| | - I-Shuo Huang
- Office of Regulatory Science, United States Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, Maryland, USA
| | - H Dail Laughinghouse
- Fort Lauderdale Research and Education Center, University of Florida - IFAS, Davie, Florida, USA
- Department of Botany, National Musuem of Natural History, Smithsonian Institution, Washington, DC, USA
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Lefler FW, Barbosa M, Zimba PV, Smyth AR, Berthold DE, Laughinghouse HD. Spatiotemporal diversity and community structure of cyanobacteria and associated bacteria in the large shallow subtropical Lake Okeechobee (Florida, United States). Front Microbiol 2023; 14:1219261. [PMID: 37711696 PMCID: PMC10499181 DOI: 10.3389/fmicb.2023.1219261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 08/14/2023] [Indexed: 09/16/2023] Open
Abstract
Lake Okeechobee is a large eutrophic, shallow, subtropical lake in south Florida, United States. Due to decades of nutrient loading and phosphorus rich sediments, the lake is eutrophic and frequently experiences cyanobacterial harmful algal blooms (cyanoHABs). In the past, surveys of the phytoplankton community structure in the lake have been conducted by morphological studies, whereas molecular based studies have been seldom employed. With increased frequency of cyanoHABs in Lake Okeechobee (e.g., 2016 and 2018 Microcystis-dominated blooms), it is imperative to determine the diversity of cyanobacterial taxa that exist within the lake and the limnological parameters that drive bloom-forming genera. A spatiotemporal study of the lake was conducted over the course of 1 year to characterize the (cyano)bacterial community structure, using 16S rRNA metabarcoding, with coincident collection of limnological parameters (e.g., nutrients, water temperature, major ions), and cyanotoxins. The objectives of this study were to elucidate spatiotemporal trends of community structure, identify drivers of community structure, and examine cyanobacteria-bacterial relationships within the lake. Results indicated that cyanobacterial communities within the lake were significantly different between the wet and dry season, but not between periods of nitrogen limitation and co-nutrient limitation. Throughout the year, the lake was primarily dominated by the picocyanobacterium Cyanobium. The bloom-forming genera Cuspidothrix, Dolichospermum, Microcystis, and Raphidiopsis were highly abundant throughout the lake and had disparate nutrient requirements and niches within the lake. Anatoxin-a, microcystins, and nodularins were detected throughout the lake across both seasons. There were no correlated (cyano)bacteria shared between the common bloom-forming cyanobacteria Dolichospermum, Microcystis, and Raphidiopsis. This study is the first of its kind to use molecular based methods to assess the cyanobacterial community structure within the lake. These data greatly improve our understanding of the cyanobacterial community structure within the lake and the physiochemical parameters which may drive the bloom-forming taxa within Lake Okeechobee.
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Affiliation(s)
- Forrest W. Lefler
- Agronomy Department, Fort Lauderdale Research and Education Center, University of Florida—IFAS, Davie, FL, United States
| | - Maximiliano Barbosa
- Agronomy Department, Fort Lauderdale Research and Education Center, University of Florida—IFAS, Davie, FL, United States
| | - Paul V. Zimba
- Rice Rivers Center, Virginia Commonwealth University, Charles City, VA, United States
| | - Ashley R. Smyth
- Soil, Water and Ecosystem Sciences Department, Tropical Research and Education Center, University of Florida—IFAS, Homestead, FL, United States
| | - David E. Berthold
- Agronomy Department, Fort Lauderdale Research and Education Center, University of Florida—IFAS, Davie, FL, United States
| | - H. Dail Laughinghouse
- Agronomy Department, Fort Lauderdale Research and Education Center, University of Florida—IFAS, Davie, FL, United States
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Massé A, Detang J, Duval C, Duperron S, Woo AC, Domart-Coulon I. Bacterial Microbiota of Ostreobium, the Coral-Isolated Chlorophyte Ectosymbiont, at Contrasted Salinities. Microorganisms 2023; 11:1318. [PMID: 37317290 DOI: 10.3390/microorganisms11051318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 06/16/2023] Open
Abstract
Microscopic filaments of the siphonous green algae Ostreobium (Ulvophyceae, Bryopsidales) colonize and dissolve the calcium carbonate skeletons of coral colonies in reefs of contrasted salinities. Here, we analyzed their bacterial community's composition and plasticity in response to salinity. Multiple cultures of Pocillopora coral-isolated Ostreobium strains from two distinct rbcL lineages representative of IndoPacific environmental phylotypes were pre-acclimatized (>9 months) to three ecologically relevant reef salinities: 32.9, 35.1, and 40.2 psu. Bacterial phylotypes were visualized for the first time at filament scale by CARD-FISH in algal tissue sections, within siphons, at their surface or in their mucilage. Ostreobium-associated microbiota, characterized by bacterial 16S rDNA metabarcoding of cultured thalli and their corresponding supernatants, were structured by host genotype (Ostreobium strain lineage), with dominant Kiloniellaceae or Rhodospirillaceae (Alphaproteobacteria, Rhodospirillales) depending on Ostreobium lineage, and shifted Rhizobiales' abundances in response to the salinity increase. A small core microbiota composed of seven ASVs (~1.5% of thalli ASVs, 19-36% cumulated proportions) was persistent across three salinities in both genotypes, with putative intracellular Amoebophilaceae and Rickettsiales_AB1, as well as Hyphomonadaceae and Rhodospirillaceae also detected within environmental (Ostreobium-colonized) Pocillopora coral skeletons. This novel knowledge on the taxonomic diversity of Ostreobium bacteria paves the way to functional interaction studies within the coral holobiont.
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Affiliation(s)
- Anaïs Massé
- Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), CNRS (UMR7245), CP54, 63 Rue Buffon, 75005 Paris, France
| | - Juliette Detang
- Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), CNRS (UMR7245), CP54, 63 Rue Buffon, 75005 Paris, France
| | - Charlotte Duval
- Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), CNRS (UMR7245), CP54, 63 Rue Buffon, 75005 Paris, France
| | - Sébastien Duperron
- Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), CNRS (UMR7245), CP54, 63 Rue Buffon, 75005 Paris, France
| | - Anthony C Woo
- Pôle Analyse de Données UAR 2700 2AD, Muséum National d'Histoire Naturelle (MNHN), 43 Rue Cuvier, 75005 Paris, France
| | - Isabelle Domart-Coulon
- Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), CNRS (UMR7245), CP54, 63 Rue Buffon, 75005 Paris, France
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Sommer V, Mikhailyuk T, Glaser K, Karsten U. Uncovering Unique Green Algae and Cyanobacteria Isolated from Biocrusts in Highly Saline Potash Tailing Pile Habitats, Using an Integrative Approach. Microorganisms 2020; 8:E1667. [PMID: 33121104 PMCID: PMC7692164 DOI: 10.3390/microorganisms8111667] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/22/2020] [Accepted: 10/22/2020] [Indexed: 02/01/2023] Open
Abstract
Potash tailing piles caused by fertilizer production shape their surroundings because of the associated salt impact. A previous study in these environments addressed the functional community "biocrust" comprising various micro- and macro-organisms inhabiting the soil surface. In that previous study, biocrust microalgae and cyanobacteria were isolated and morphologically identified amongst an ecological discussion. However, morphological species identification maybe is difficult because of phenotypic plasticity, which might lead to misidentifications. The present study revisited the earlier species list using an integrative approach, including molecular methods. Seventy-six strains were sequenced using the markers small subunit (SSU) rRNA gene and internal transcribed spacer (ITS). Phylogenetic analyses confirmed some morphologically identified species. However, several other strains could only be identified at the genus level. This indicates a high proportion of possibly unknown taxa, underlined by the low congruence of the previous morphological identifications to our results. In general, the integrative approach resulted in more precise species identifications and should be considered as an extension of the previous morphological species list. The majority of taxa found were common in saline habitats, whereas some were more likely to occur in nonsaline environments. Consequently, biocrusts in saline environments of potash tailing piles contain unique microalgae and cyanobacteria that will possibly reveal several new taxa in more detailed future studies and, hence, provide new data on the biodiversity, as well as new candidates for applied research.
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Affiliation(s)
- Veronika Sommer
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
- upi UmweltProjekt Ingenieursgesellschaft mbH, 39576 Stendal, Germany
| | - Tatiana Mikhailyuk
- National Academy of Sciences of Ukraine, M.G. Kholodny Institute of Botany, 01601 Kyiv, Ukraine;
| | - Karin Glaser
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
| | - Ulf Karsten
- Institute for Biological Sciences, Applied Ecology and Phycology, University of Rostock, 18059 Rostock, Germany; (V.S.); (K.G.)
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