lnu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 20) Show all publications
Sörenson, E., Bertos-Fortis, M., Farnelid, H., Kremp, A., Kruget, K., Lindehoff, E. & Legrand, C. (2019). Consistency in microbiomes in cultures of Alexandrium species isolated from brackish and marine waters. Environmental Microbiology Reports, 11(3), 425-433
Open this publication in new window or tab >>Consistency in microbiomes in cultures of Alexandrium species isolated from brackish and marine waters
Show others...
2019 (English)In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 11, no 3, p. 425-433Article in journal (Refereed) Published
Abstract [en]

Phytoplankton and bacteria interactions have a significant role in aquatic ecosystem functioning. Associations can range from mutualistic to parasitic, shaping biogeochemical cycles and having a direct influence on phytoplankton growth. How variations in phenotype and sampling location, affect the phytoplankton microbiome is largely unknown. A high‐resolution characterization of the bacterial community in cultures of the dinoflagellate Alexandrium was performed on strains isolated from different geographical locations and at varying anthropogenic impact levels. Microbiomes of Baltic Sea Alexandrium ostenfeldii isolates were dominated by Betaproteobacteria and were consistent over phenotypic and genotypic Alexandrium strain variation, resulting in identification of an A. ostenfeldii core microbiome. Comparisons with in situ bacterial communities showed that taxa found in this A. ostenfeldii core were specifically associated to dinoflagellate dynamics in the Baltic Sea. Microbiomes of Alexandrium tamarense and minutum, isolated from the Mediterranean Sea, differed from those of A. ostenfeldii in bacterial diversity and composition but displayed high consistency, and a core set of bacterial taxa was identified. This indicates that Alexandrium isolates with diverse phenotypes host predictable, species‐specific, core microbiomes reflecting the abiotic conditions from which they were isolated. These findings enable in‐depth studies of potential interactions occurring between Alexandrium and specific bacterial taxa.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
Keywords
Algae, Bacteria, Interactions, Microbiome, Baltic Sea, Alexandrium, Alger, Bakterier, Interaktioner, Microbiom, Östersjön, Alexandrium
National Category
Ecology Microbiology
Research subject
Ecology, Microbiology; Ecology, Aquatic Ecology
Identifiers
urn:nbn:se:lnu:diva-81534 (URN)10.1111/1758-2229.12736 (DOI)000468000600014 ()30672139 (PubMedID)2-s2.0-85062772299 (Scopus ID)
Projects
EcoChange
Funder
Swedish Research Council FormasEU, European Research Council, 659453EU, Horizon 2020, 659453Carl Tryggers foundation , 14:283
Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-08-29Bibliographically approved
Farnelid, H., Turk-Kubo, K., Ploug, H., Ossolinski, J. E., Collins, J. R., van Mooy, B. A. S. & Zehr, J. P. (2019). Diverse diazotrophs are present on sinking particles in the North Pacific Subtropical Gyre. The ISME Journal, 13(1), 170-182
Open this publication in new window or tab >>Diverse diazotrophs are present on sinking particles in the North Pacific Subtropical Gyre
Show others...
2019 (English)In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 13, no 1, p. 170-182Article in journal (Refereed) Published
Abstract [en]

Sinking particles transport carbon and nutrients from the surface ocean into the deep sea and are considered hot spots for bacterial diversity and activity. In the oligotrophic oceans, nitrogen (N-2)-fixing organisms (diazotrophs) are an important source of new N but the extent to which these organisms are present and exported on sinking particles is not well known. Sinking particles were collected every 6 h over a 2-day period using net traps deployed at 150 m in the North Pacific Subtropical Gyre. The bacterial community and composition of diazotrophs associated with individual and bulk sinking particles was assessed using 16S rRNA and nifH gene amplicon sequencing. The bacterial community composition in bulk particles remained remarkably consistent throughout time and space while large variations of individually picked particles were observed. This difference suggests that unique biogeochemical conditions within individual particles may offer distinct ecological niches for specialized bacterial taxa. Compared to surrounding seawater, particle samples were enriched in different size classes of globally significant N-2-fixing cyanobacteria including Trichodesmium, symbionts of diatoms, and the unicellular cyanobacteria Crocosphaera and UCYN-A. The particles also contained nifH gene sequences of diverse non-cyanobacterial diazotrophs suggesting that particles could be loci for N-2 fixation by heterotrophic bacteria. The results demonstrate that diverse diazotrophs were present on particles and that new N may thereby be directly exported from surface waters on sinking particles.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Ecology Microbiology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-79741 (URN)10.1038/s41396-018-0259-x (DOI)000453576600014 ()30116043 (PubMedID)2-s2.0-85052502520 (Scopus ID)
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-08-29Bibliographically approved
del Carmen Munoz-Marin, M., Shilova, I. N., Shi, T., Farnelid, H., Maria Cabello, A. & Zehr, J. P. (2019). The Transcriptional Cycle Is Suited to Daytime N2 Fixation in the Unicellular Cyanobacterium “Candidatus Atelocyanobacterium thalassa” (UCYN-A). mBio, 10(1), 1-17, Article ID e02495-18.
Open this publication in new window or tab >>The Transcriptional Cycle Is Suited to Daytime N2 Fixation in the Unicellular Cyanobacterium “Candidatus Atelocyanobacterium thalassa” (UCYN-A)
Show others...
2019 (English)In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 10, no 1, p. 1-17, article id e02495-18Article in journal (Refereed) Published
Abstract [en]

Symbiosis between a marine alga and a N-2-fixing cyanobacterium (Cyanobacterium UCYN-A) is geographically widespread in the oceans and is important in the marine N cycle. UCYN-A is uncultivated and is an unusual unicellular cyanobacterium because it lacks many metabolic functions, including oxygenic photosynthesis and carbon fixation, which are typical in cyanobacteria. It is now presumed to be an obligate symbiont of haptophytes closely related to Braarudosphaera bigelowii. N-2-fixing cyanobacteria use different strategies to avoid inhibition of N-2 fixation by the oxygen evolved in photosynthesis. Most unicellular cyanobacteria temporally separate the two incompatible activities by fixing N-2 only at night, but, surprisingly, UCYN-A appears to fix N-2 during the day. The goal of this study was to determine how the unicellular UCYN-A strain coordinates N-2 fixation and general metabolism compared to other marine cyanobacteria. We found that UCYN-A has distinct daily cycles of many genes despite the fact that it lacks two of the three circadian clock genes found in most cyanobacteria. We also found that the transcription patterns in UCYN-A are more similar to those in marine cyanobacteria that are capable of aerobic N-2 fixation in the light, such as Trichodesmium and heterocyst-forming cyanobacteria, than to those in Crocosphaera or Cyanothece species, which are more closely related to unicellular marine cyanobacteria evolutionarily. Our findings suggest that the symbiotic interaction has resulted in a shift of transcriptional regulation to coordinate UCYN-A metabolism with that of the phototrophic eukaryotic host, thus allowing efficient coupling of N-2 fixation (by the cyanobacterium) to the energy obtained from photosynthesis (by the eukaryotic unicellular alga) in the light. IMPORTANCE The symbiotic N-2-fixing cyanobacterium UCYN-A, which is closely related to Braarudosphaera bigelowii, and its eukaryotic algal host have been shown to be globally distributed and important in open-ocean N-2 fixation. These unique cyanobacteria have reduced metabolic capabilities, even lacking genes for oxygenic photosynthesis and carbon fixation. Cyanobacteria generally use energy from photosynthesis for nitrogen fixation but require mechanisms for avoiding inactivation of the oxygen-sensitive nitrogenase enzyme by ambient oxygen (O-2) or the O-2 evolved through photosynthesis. This study showed that symbiosis between the N-2-fixing cyanobacterium UCYN-A and its eukaryotic algal host has led to adaptation of its daily gene expression pattern in order to enable daytime aerobic N-2 fixation, which is likely more energetically efficient than fixing N-2 at night, as found in other unicellular marine cyanobacteria.

Place, publisher, year, edition, pages
American Society of Microbiology, 2019
Keywords
cyanobacteria, diel cycle, marine microbiology, nitrogen fixation, symbiosis, whole-genome expression
National Category
Microbiology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-81227 (URN)10.1128/mBio.02495-18 (DOI)000460314300043 ()30602582 (PubMedID)2-s2.0-85059502692 (Scopus ID)
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-08-29Bibliographically approved
Cornejo-Castillo, F. M., del Carmen Munoz-Marin, M., Turk-Kubo, K. A., Royo-Llonch, M., Farnelid, H., Acinas, S. G. & Zehr, J. P. (2019). UCYN-A3, a newly characterized open ocean sublineage of the symbiotic N2-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa. Environmental Microbiology, 21(1), 111-124
Open this publication in new window or tab >>UCYN-A3, a newly characterized open ocean sublineage of the symbiotic N2-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa
Show others...
2019 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 21, no 1, p. 111-124Article in journal (Refereed) Published
Abstract [en]

The symbiotic unicellular cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is one of the most abundant and widespread nitrogen (N-2)-fixing cyanobacteria in the ocean. Although it remains uncultivated, multiple sublineages have been detected based on partial nitrogenase (nifH) gene sequences, including the four most commonly detected sublineages UCYN-A1, UCYN-A2, UCYN-A3 and UCYN-A4. However, very little is known about UCYN-A3 beyond the nifH sequences from nifH gene diversity surveys. In this study, single cell sorting, DNA sequencing, qPCR and CARD-FISH assays revealed discrepancies involving the identification of sublineages, which led to new information on the diversity of the UCYN-A symbiosis. 16S rRNA and nifH gene sequencing on single sorted cells allowed us to identify the 16S rRNA gene of the uncharacterized UCYN-A3 sublineage. We designed new CARD-FISH probes that allowed us to distinguish and observe UCYN-A2 in a coastal location (SIO Pier; San Diego) and UCYN-A3 in an open ocean location (Station ALOHA; Hawaii). Moreover, we reconstructed about 13% of the UCYN-A3 genome from Tara Oceans metagenomic data. Finally, our findings unveil the UCYN-A3 symbiosis in open ocean waters suggesting that the different UCYN-A sublineages are distributed along different size fractions of the plankton defined by the cell-size ranges of their prymnesiophyte hosts.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
National Category
Microbiology Ecology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-80287 (URN)10.1111/1462-2920.14429 (DOI)000456278900008 ()30255541 (PubMedID)2-s2.0-85056280294 (Scopus ID)
Available from: 2019-02-08 Created: 2019-02-08 Last updated: 2019-08-29Bibliographically approved
Turk-Kubo, K. A., Connell, P., Caron, D., Hogan, M. E., Farnelid, H. & Zehr, J. P. (2018). In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre. Frontiers in Microbiology, 9, Article ID 1616.
Open this publication in new window or tab >>In Situ Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre
Show others...
2018 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 1616Article in journal (Refereed) Published
Abstract [en]

Major advances in understanding the diversity, distribution, and activity of marine N-2-fixing microorganisms (diazotrophs) have been made in the past decades, however, large gaps in knowledge remain about the environmental controls on growth and mortality rates. In order to measure diazotroph net growth rates and microzooplankton grazing rates on diazotrophs, nutrient perturbation experiments and dilution grazing experiments were conducted using free-floating in situ incubation arrays in the vicinity of Station ALOHA in March 2016. Net growth rates for targeted diazotroph taxa as well as Prochlorococcus, Synechococcus and photosynthetic picoeukaryotes were determined under high (H) and low (L) nitrate:phosphate (NP) ratio conditions at four depths in the photic zone (25, 45, 75, and 100 m) using quantitative PCR and flow cytometry. Changes in the prokaryote community composition in response to HNP and LNP treatments were characterized using 16S rRNA variable region tag sequencing. Microzooplankton grazing rates on diazotrophs were measured using a modified dilution technique at two depths in the photic zone (15 and 125 m). Net growth rates for most of the targeted diazotrophs after 48 h were not stimulated as expected by LNP conditions, rather enhanced growth rates were often measured in HNP treatments. Interestingly, net growth rates of the uncultivated prymnesiophyte symbiont UCYN-Al were stimulated in HNP treatments at 75 and 100 m, suggesting that N used for growth was acquired through continuing to fix N-2 in the presence of nitrate. Net growth rates for UCYN-Al , UCYN-C, Crocosphaera sp. (UCYN-B) and the diatom symbiont Richelia (associated with Rhizosolenia) were uniformly high at 45 m (up to 1.6 +/- 0.5 d(-1)), implying that all were growing optimally at the onset of the experiment at that depth. Differences in microzooplankton grazing rates on UCYN-Al and UCYN-C in 15 m waters indicate that the grazer assemblage preyed preferentially on UCYN-Al. Deeper in the water column (125 m), both diazotrophs were grazed at substantial rates, suggesting grazing pressure may increase with depth in the photic zone. Constraining in situ diazotroph growth and mortality rates are important steps for improving parameterization for diazotrophs in global ecosystem models.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
diazotroph, growth rates, mortality rates, in situ incubations, dilution technique, nifH, qPCR
National Category
Microbiology Ecology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-77394 (URN)10.3389/fmicb.2018.01616 (DOI)000439754200001 ()30090092 (PubMedID)2-s2.0-85050456305 (Scopus ID)
Available from: 2018-08-30 Created: 2018-08-30 Last updated: 2019-08-29Bibliographically approved
Turk-Kubo, K. A., Farnelid, H., Shilova, I. N., Henke, B. & Zehr, J. P. (2017). Distinct ecological niches of marine symbiotic N2-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa sublineages. Journal of Phycology, 53(2), 451-461
Open this publication in new window or tab >>Distinct ecological niches of marine symbiotic N2-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa sublineages
Show others...
2017 (English)In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 53, no 2, p. 451-461Article in journal (Refereed) Published
Abstract [en]

A recently described symbiosis between the metabolically streamlined nitrogen-fixing cyanobacterium UCYN-A and a single-celled eukaryote prymnesiophyte alga is widely distributed throughout tropical and subtropical marine waters, and is thought to contribute significantly to nitrogen fixation in these regions. Several UCYN-A sublineages have been defined based on UCYN-A nitrogenase (nifH) sequences. Due to the low abundances of UCYN-A in the global oceans, currently existing molecular techniques are limited for detecting and quantifying these organisms. A targeted approach is needed to adequately characterize the diversity of this important marine cyanobacterium, and to advance understanding of its ecological importance. We present findings on the distribution of UCYN-A sublineages based on high throughput sequencing of UCYN-A nifH PCR amplicons from 78 samples distributed throughout many major oceanic provinces. These UCYN-A nifH fragments were used to define oligotypes, alternative taxonomic units defined by nucleotide positions with high variability. The data set was dominated by a single oligotype associated with the UCYN-A1 sublineage, consistent with previous observations of relatively high abundances in tropical and subtropical regions. However, this analysis also revealed for the first time the widespread distribution of the UCYN-A3 sublineage in oligotrophic waters. Furthermore, distinct assemblages of UCYN-A oligotypes were found in oligotrophic and coastally influenced waters. This unique data set provides a framework for determining the environmental controls on UCYN-A distributions and the ecological importance of the different sublineages.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
Candidatus Atelocyanobacterium thalassa, UCYN-A, nifH, Nitrogen fixation, Nitrogenase, Oligotyping
National Category
Microbiology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-62271 (URN)10.1111/jpy.12505 (DOI)000399745800020 ()27992651 (PubMedID)2-s2.0-85010966961 (Scopus ID)
Projects
EcoChange
Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2019-08-29Bibliographically approved
Zehr, J. P., Shilova, I. N., Farnelid, H., Muñoz-Marín, M. d. & Turk-Kubo, K. A. (2017). Unusual marine unicellular symbiosis with the nitrogen-fixing cyanobacterium UCYN-A. Nature Microbiology, 2(1), 1-10, Article ID 16214.
Open this publication in new window or tab >>Unusual marine unicellular symbiosis with the nitrogen-fixing cyanobacterium UCYN-A
Show others...
2017 (English)In: Nature Microbiology, E-ISSN 2058-5276, Vol. 2, no 1, p. 1-10, article id 16214Article in journal (Refereed) Published
Abstract [en]

Nitrogen fixation — the reduction of dinitrogen (N2) gas to biologically available nitrogen (N) — is an important source of N for terrestrial and aquatic ecosystems. In terrestrial environments, N2-fixing symbioses involve multicellular plants, but in the marine environment these symbioses occur with unicellular planktonic algae. An unusual symbiosis between an uncultivated unicellular cyanobacterium (UCYN-A) and a haptophyte picoplankton alga was recently discovered in oligotrophic oceans. UCYN-A has a highly reduced genome, and exchanges fixed N for fixed carbon with its host. This symbiosis bears some resemblance to symbioses found in freshwater ecosystems. UCYN-A shares many core genes with the ‘spheroid bodies’ of Epithemia turgida and the endosymbionts of the amoeba Paulinella chromatophora. UCYN-A is widely distributed, and has diversified into a number of sublineages that could be ecotypes. Many questions remain regarding the physical and genetic mechanisms of the association, but UCYN-A is an intriguing model for contemplating the evolution of N2-fixing organelles.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
Keywords
Applied microbiology, Ecology, Microbial biooceanography, Microbial ecology, Symbiosis
National Category
Ecology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-72636 (URN)10.1038/nmicrobiol.2016.214 (DOI)000396366300020 ()27996008 (PubMedID)2-s2.0-85006797160 (Scopus ID)
Projects
EcoChange
Note

Correction published in Nature Microbiology 2(3):17016. DOI: 10.1038/nmicrobiol.2017.16

Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2019-08-29Bibliographically approved
Farnelid, H., Turk-Kubo, K. A. & Zehr, J. P. (2016). Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters. Frontiers in Microbiology, 7, Article ID 339.
Open this publication in new window or tab >>Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters
2016 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, article id 339Article in journal (Refereed) Published
Abstract [en]

Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes. Samples were collected at the Santa Cruz wharf on Monterey Bay, CA, USA during summer and fall, 2014. The phylogeny of associated microbes was assessed through 16S rRNA gene amplicon clone and Illumina MiSeq libraries. The most frequently detected bacterioplankton phyla within the photosynthetic picoeukaryote sorts were Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) and Bacteroidetes. Intriguingly, the presence of free-living bacterial genera in the photosynthetic picoeukaryote sorts could suggest that some of the photosynthetic picoeukaryotes were mixotrophs. However, the occurrence of bacterial sequences, which were not prevalent in the corresponding bulk seawater samples, indicates that there was also a selection for specific OTUs in association with photosynthetic picoeukaryotes suggesting specific functional associations. The results show that diverse bacterial phylotypes are found in association with photosynthetic picoeukaryotes. Taxonomic identification of these associations is a prerequisite for further characterizing and to elucidate their metabolic pathways and ecological functions.

Keywords
microbial associations, bacterivory, flow cytometry, photosynthetic picoeukaryotes, symbiosis
National Category
Microbiology
Research subject
Ecology, Microbiology
Identifiers
urn:nbn:se:lnu:diva-52117 (URN)10.3389/fmicb.2016.00339 (DOI)000372495500001 ()2-s2.0-84964316472 (Scopus ID)
Projects
EcoChange
Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2018-11-15Bibliographically approved
Farnelid, H., Turk-Kubo, K., del Carmen Munoz-Marin, M. & Zehr, J. P. (2016). New insights into the ecology of the globally significant uncultured nitrogen-fixing symbiont UCYN-A. Aquatic Microbial Ecology, 77(3), 125-138
Open this publication in new window or tab >>New insights into the ecology of the globally significant uncultured nitrogen-fixing symbiont UCYN-A
2016 (English)In: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 77, no 3, p. 125-138Article, review/survey (Refereed) Published
Abstract [en]

Cyanobacterial nitrogen-fixers (diazotrophs) play a key role in biogeochemical cycling of carbon and nitrogen in the ocean. In recent years, the unusual symbiotic diazotrophic cyanobacterium Atelocyanobacterium thalassa (UCYN-A) has been recognized as one of the major diazotrophs in the tropical and subtropical oceans. In this review, we summarize what is currently known about the geographic distribution of UCYN-A, as well as the environmental factors that govern its distribution. In addition, by compiling UCYN-A nifH sequences from the GenBank no. database as well as those from nifH gene amplicon next generation sequencing studies, we present an in-depth analysis of the distribution of defined UCYN-A sublineages (UCYN-A1, UCYN-A2 and UCYN-A3) and identify a novel sublineage, UCYN-A4, which may be significant in some environments. Each UCYN-A sublineage exhibited a remarkable global distribution pattern and several UCYN-A sublineages frequently co-occurred within the same sample, suggesting that if they represent different ecotypes they have overlapping niches. Recently, single cell visualization techniques using specific probes targeting UCYN-A1 and UCYN-A2 and their respective associated eukaryotic partner cells showed that the size of the consortia and the number of UCYN-A cells differed between these 2 sublineages. Combined, the results highlight that UCYN-A sublineages likely have different physiological requirements, which need to be accounted for in future studies. Furthermore, based on our increasing knowledge of the diversity of the UCYN-A lineage, we discuss some of the limitations of currently used cultivation-independent molecular techniques for the identification and quantification of UCYN-A.

Keywords
UCYN-A, Symbiosis, nifH, qPCR, Next generation amplicon sequencing, CARD-FISH, Braarudosphaera bigelowii
National Category
Ecology Microbiology
Research subject
Ecology, Aquatic Ecology
Identifiers
urn:nbn:se:lnu:diva-59023 (URN)10.3354/ame01794 (DOI)000387120300001 ()2-s2.0-84991829529 (Scopus ID)
Projects
EcoChange
Available from: 2016-12-14 Created: 2016-12-14 Last updated: 2018-04-24Bibliographically approved
Bertos-Fortis, M., Farnelid, H., Lindh, M. V., Casini, M., Andersson, A., Pinhassi, J. & Legrand, C. (2016). Unscrambling Cyanobacteria Community Dynamics Related to Environmental Factors. Frontiers in Microbiology, 7, Article ID 625.
Open this publication in new window or tab >>Unscrambling Cyanobacteria Community Dynamics Related to Environmental Factors
Show others...
2016 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, article id 625Article in journal (Refereed) Published
Abstract [en]

Future climate scenarios in the Baltic Sea project an increase of cyanobacterial bloom frequency and duration, attributed to eutrophication and climate change. Some cyanobacteria can be toxic and their impact on ecosystem services is relevant for a sustainable sea. Yet, there is limited understanding of the mechanisms regulating cyanobacterial diversity and biogeography. Here we unravel successional patterns and changes in cyanobacterial community structure using a 2-year monthly time series during the productive season in a 100 km coastal-offshore transect using microscopy and high-throughput sequencing of 16S rRNA gene fragments. A total of 565 cyanobacterial OTUs were found, of which 231 where filamentous/colonial and 334 picocyanobacterial. Spatial differences in community structure between coastal and offshore waters were minor. An "epidemic population structure" (dominance of a single cluster) was found for Aphanizomenon/Dolichospermum within the filamentous/colonial cyanobacterial community. In summer, this cluster simultaneously occurred with opportunistic clusters/OTUs, e.g., Nodulana spumigena and Pseudanabaena. Picocyanobacteria, Synechococcus/Cyanobium, formed a consistent but highly diverse group. Overall, the potential drivers structuring summer cyanobacterial communities were temperature and salinity. However, the different responses to environmental factors among and within genera suggest high niche specificity for individual OTUs. The recruitment and occurrence of potentially toxic filamentous/colonial clusters was likely related to disturbance such as mixing events and short-term shifts in salinity, and not solely dependent on increasing temperature and nitrogen-limiting conditions. Nutrients did not explain further the changes in cyanobacterial community composition. Novel occurrence patterns were identified as a strong seasonal succession revealing a tight coupling between the emergence of opportunistic picocyanobacteria and the bloom of filamentous/colonial clusters. These findings highlight that if environmental conditions can partially explain the presence of opportunistic picocyanobacteria, microbial and trophic interactions with filamentous/colonial cyanobacteria should also be considered as potential shaping factors for single-celled communities. Regional climate change scenarios in the Baltic Sea predict environmental shifts leading to higher temperature and lower salinity; conditions identified here as favorable for opportunistic filamentous/colonial cyanobacteria. Altogether, the diversity and complexity of cyanobacterial communities reported here is far greater than previously known, emphasizing the importance of microbial interactions between filamentous and picocyanobacteria in the context of environmental disturbances.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2016
Keywords
cyanobacteria, community, environmental factors, climate change, temperature, salinity
National Category
Microbiology Ecology
Research subject
Ecology, Aquatic Ecology
Identifiers
urn:nbn:se:lnu:diva-53266 (URN)10.3389/fmicb.2016.00625 (DOI)000375401300001 ()2-s2.0-84973580285 (Scopus ID)
Projects
EcoChange
Available from: 2016-06-10 Created: 2016-06-10 Last updated: 2018-10-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3083-7437

Search in DiVA

Show all publications