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  1. Sebastian Coloma
  2. Simon Dittami
  3. Alexander Eiler
  4. Friederike Eimer
  5. Swantje Enge
  6. Angelique Gobet
  7. Hans Peter Grossart
  8. Stina Jakobsson
  9. Oskar Johansson
  10. Tomas Larsson
  11. Markus Lindh
  12. Kai Lohbeck
  13. Vaskar Mukherjee
  14. Sigvard Olofsson
  15. Matt Pinder (poster) 
  16. Jarone Pinhassi
  17. Helle Ploug
  18. Peter Steinberg
  19. Luca Zoccarato

Role of cyanophages on filamentous cyanobacteria populations, nutrient cycling and plankton community dynamics

Sebastian Coloma
Cyanobacteria like most organisms, are strongly influenced by ecological interactions such as competition, predation and parasitism. It has been studied that parasitic viruses (i.e. cyanophages) can reduce significantly cyanobacterial biomass and generate a selective force for the host genotypes. In addition, this interaction can have also a wider impact on the nutrient environment. Since, nitrogen is the limiting nutrient for phytoplankton and cyanobacterial growth in the Baltic Sea, it is important to study viruses effect on rapid increase of nitrogen in the local aquatic environment. We are aiming to clarify and define the relations between filamentous cyanobacteria and cyanophages, and the resulting nitrogen release, diversification of the host and the final effect on plankton community structures through an experimental approach. These dynamics are altered if host population becomes resistant to the viral infection. In here we demonstrate that cyanophages can be one of the key groups in aquatic food webs and we also link eco-evolutionary host-parasites dynamics with biogeochemical cycles and plankton community dynamics.

Bacterial interactions and their impact on stress tolerance in the model brown alga Ecotcarpus.

Simon Dittami

Considering bacteria is key to understanding the biology and evolution of algae. For example, one of the few known freshwater brown algae, a strain of Ectocarpus from Hopkins River Falls, Victoria, Australia depends on bacteria to grow in fresh water: cultures that have been deprived of their associated microbiome do not survive the transfer to freshwater, but restoring the associated microflora also brings back the capacity to acclimate to this change. We have attempted to simplify this system with antibiotics treatments, and to test the effect of different bacteria extracted isolated from the holobiont using a range of cultivation techniques. Although individual cultivable bacterial strains did not have a strong effect on freshwater tolerance, we were able to generate distinct holobiont communities that differ in salinity tolerance. Metagenomic-, metatranscriptomic-, and metabolite analyses of these communities are currently ongoing. The resulting data can be integrated and analyzed based on simplified metabolic models of both algae and bacteria. This analysis is facilitated by bioinformatics toolbox recently developed by our collaborators at the IRISA Rennes, the Padmet-box. We anticipate this approach will prove valuable to study metabolic host-symbiont interactions both in controlled laboratory- and, in the long run, in natural conditions.

From metacommunity theory to systems biology in vertebrate microbiomes

Alexander Eiler

Fish harbor diverse communities of symbiotic microbes that interact with the hosts and affect important fitness components. Applying metacommunity theory, we found that environmental factors including fish habitat, fish species, their diet, dispersal factors including microbes from fish diet, and ecological drift contributed to the assembly of fish gut microbial communities. The proportion of their contribution varied between fish species. In addition, we show that (predation) stress determines gut microbiota and fitness components of fish. Stress responses depended on sex and diet with feedbacks on host fitness components. While responses in the microbiome to host condition have been described in much detail, the feedbacks of the microbiome on their host are often not well understood, so are their dynamics over evolutionary time scales. With my presentation I would like to initiate a discussion on the co-evolutinonary processes in stress resistance in vertebrate-microbiome systems, in particular in the light of current climate change.

Marine microbes influence the life cycle of macroalgae

Friederike Eimer

Seaweed surfaces offer a playground for interactive and complex microbial communities including bacteria, fungi, spores, diatoms and even larvae stages of marine invertebrates. These interactions do not leave the seaweed host unaffected and can influence growth, morphology, sporulation and spore settlement, the ladder being influenced by external microbial communities. Marine surfaces are quickly colonised by microbial biofilm-forming communities and provide primary substratum for settlement of motile seaweed spores. Previous studies on the spore settlement of the green seaweed Enteromorpha have shown a positive correlation between the number of attached zoospores and the number of bacteria present in a natural asssemblage. Bacterial influence on spore settlement is well studied in Ulvaceans, but little information on the spore settlement of the brown seaweed Saccharina latissima is response to bacterial biofilms is available. Similar to Ulva zoospores, Saccharina spores are highly motile and negatively phototactic which makes it an ideal study organism. During an experiment, we examined if bacterially mediated biofilms facilitated spore settlement of the commercially valuable brown seaweed Saccharina lattissima.
Epiphytic and endophytic microbes can also influence growth of their seaweed host. Thallusin, a bacterial metabolite, has been shown to play a crucial role in the morphogenesis of marine macroalgae. Furthermore, nitrogen-fixating bacteria can initiate growth, especially in areas where nitrogen availability is limited. In a second experiment, we tested bacterial strains that were isolated from the surface of Ulva lactuca on their growth inducing capabilities. Results from both experiments will be presented during the CeMEB assembly.

Untargeted metabolomics as a first step to elucidate phytoalexins in Barbarea vulgaris var arcuata against the oomycete pathogen Albugo sp.

Swantje Engea,b, Christoph Crocolla, Søren Baka and Thure Hauseraa

a -Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
b - Institute of the Chemistry and Biology of the Marine Environment, University of Oldenburg, Germany

The yellow rocket cress Barbarea vulgaris var arcuate (Brassicaceae) has two recognised chemotypes differing morphologically in leaf pubescence and chemically in their composition of secondary metabolites, i.e. saponins, glucosinolates and flavonoids. The glabrous type (G-type) is resistant to insect herbivores, i.e. the flea beetle Phyllotreta nemorum or the diamond back moth Plutella xylostella, but susceptible to the white rust pathogen Albugo sp.. In contrast, the pubescent type (P-type) is essentially resistant to white rust but highly susceptible to herbivores. Several G-type specific saponins could be identified to constitute resistance against herbivores, whereas it is still unknown what determines the resistance against Albugo sp. in the P-type. Besides short-term responses, i.e. oxidative burst, apoptosis or callose deposition, plants can resist pathogen infection through the production of antimicrobial substances, so called phytoalexins. The aim of this study was to examine if secondary metabolites are likely to be involved in the resistance of the P-type of B. vulgaris against Albugo sp.. Second generation off-springs of artificially crossed P-and G-type plants as well as off-springs of a natural hybrid population were inoculated with the white rust pathogen and the development of infection symptoms were recorded, which was the case for about 40 % of the inoculated plants. Untargeted metabolomics by LC-QTOF mass spectrometry was then used to acquire the chemical profiles of resistant and susceptible hybrids, which were further analysed by univariate and multivariate PLS-DA models to detect compounds relating to resistance. About 150 compounds that correspond to differences in resistant and susceptible plants were identified by PLS-DA VIP scores, Vulcano plots and ROC curve based biomarker analysis. Comparisons of inoculated and control P- and G-type plants by ANOVA and Vulcano plots reduced the number to 69 candidate compounds. These were either small, highly polar molecules or glycosylated flavonoids with phenylpropanoid substitutes as identified by metabolite library searches. None of the features were significantly up-regulated in inoculated P-type plants compared to the P-type controls indicating that the compounds relating to resistance are constitutively produced rather than induced.

Seasonal and diet-driven assembly of a core microbiota associated to macroalgal digestion in the marine herbivore holobiont

Angélique Gobet1, Laëtitia Mest1, Morgan Perennou2, Simon Dittami1, Claire Caralp3, Céline Coulombet4, Sylvain Huchette4, Sabine Roussel3, Gurvan Michel1 and Catherine Leblanc1

1UMR 8227 CNRS UPMC, LBI2M, Station Biologique de Roscoff (SBR), France
2Genomer & ABiMS platforms, FR 2424 CNRS UPMC, SBR, France
3LEMAR, UMR 6539, IUEM, Plouzané, France
4France Haliotis, Plouguerneau, France

The importance of host digestive microbiota is increasingly coming into the focus of ecological and clinical research due to their major role in host digestion, host health and host development. There are numerous studies on the digestive microbiota of mammals and terrestrial herbivores but little is known about marine herbivores. Among them, generalists consume red, green, and brown algae, each presenting specific composition in complex polysaccharides. Subsequently, each macroalga presents a specific epiphytic microbiota and the digestive microbiota of marine herbivore is expected to vary with a monospecific algal diet. Therefore, we investigated the effect of 4 monospecific diets (Palmaria palmata, Ulva lactuca, Saccharina latissima, Laminaria digitata) on the digestive microbiota of a generalist marine herbivore in its natural environment over one year. Our model is a generalist herbivore able to digest the 3 algal types; the abalone, a gastropod of primary interest due to its economic importance in several countries in Asia, South Africa, and South America. The microbiota from abalone digestive gland, sampled every 2 months, was explored using metabarcoding. Despite differences in algal diet composition, we unexpectedly found three bacterial genera that constantly dominated the community: Psychrilyobacter, Mycoplasma, and Vibrio. Phylogenetically close genomes indicated their ability to ferment pyruvate and only Vibrio seemed able to degrade alginate from brown macroalgae. Key aerobic primary degraders of algal polysaccharides were found in a less abundant core microbiota associated with each algal diet. Despite finding few diet-specific OTUs, diversity analyses showed diet-specific patterns of the bacterial community and this was further confirmed by correlations between individual bacterial groups and algal characteristics. Abalone digestive gland may represent a particular niche where abalone-specific bacteria cohabit with transient bacteria able to degrade algal polysaccharides.

Bacteria interacting with dead and live surfaces in aquatic ecosystems

Hans Peter Grossart and the MIBI team

Bacteria have multiple lifestyles and are attracted by all kind of surfaces including detritus and living organism. Chemotaxis, attachment and biofilm formation are important bacterial adaptations to the surface-associated lifestyle. Many studies show that interactions between bacteria and surfaces, in particular with living organisms, have severe consequences for bacterial physiology and evolution, but also for the organisms they are interacting with. Bacteria-phytoplankton interactions are ideal model systems to study the interdependencies between both partners and their ecological implications. Thereby the algal microbiome affects growth and health of their phytoplankton partner rendering bacteria-phytoplankton interactions highly dynamic in time and space. Recent development of molecular methods has open up exciting insights into the underlying mechanisms including gene regulation and exchange. In my talk, I will highlight a few examples on how microbial life on surfaces affects organic matter cycling and address specific interactions between bacteria with phyto- and zooplankton and their ecological consequences for organic matter and nutrient cycling by taking their environmental context into account.

Seagrass infection along a salinity gradient

Stina Jakobsson

Marine pathogens can have a devastating impact on their hosts and the surrounding ecosystems. This was seen in the 1930’s when the wasting disease pathogen Labyrinthula zosterae killed 90% of the seagrass Zostera marina in the Atlantic Ocean. Many of the surviving Z. marina populations were found in low salinity environments, indicating that low salinity can mitigate the infection. Although laboratory studies have detected a correlation between L. zosterae infection and salinity, the lack of extensive field investigations makes it difficult to corroborate the ecological relevance of these findings. Thus, the aim of this field study was to measure the severity of wasting disease on Z. marina shoots from different salinity populations (6 - 30 PSU) along the Swedish coastline. Results show that prevalence and abundance of L. zosterae decreases along with the salinity gradient. However, an unexplained increase in infection was detected at the lowest salinity (6 PSU). In addition, experimental work shows that all shoots, independent of origin, are susceptible to the pathogen, and that chemical defense abilities cannot be linked to pathogen pressure. This is the first field study to show that L. zosterae infection on Z. marina decreases along with salinity. It also raises the question whether controlling factors of this host-pathogen interaction are changing.

A functional genomics approach to the Skeletonema microbiome

Oskar Johansson

The genome of the diatom Skeletonema marinoi was sequenced during 2016. As a consequence several bacterial genomes were identified among the sequence reads. An attempt was made to isolate independent bacteria from the S.marinoi holoculture. This led to the identification of 9 independent bacterial strains distributed over two S.marinoi isolates. Recently, successful genetic transformation of S. marinoi was achieved in our laboratory in Gothenburg. The method has proven to be able to produce stable lines with insertions that can attenuate gene expression. These transformed cell lines can now be mapped to precise location within the S.marinoi genome. A pilot trial has produced evidence towards a growth enhancing effect of one of the isolated strains. We are now setting up a forward genetic screen of our mutant library to identify key genes in this interaction. 

The IMAGO genome projects - current status and future plans

Tomas Larsson

I will give a short update on the progress and status of the IMAGO projects. Special focus will be put on how potential users can access and use the available sequencing data and plans for improving usability of these databases. A few examples will be given from projects in different stages of completion.

From applied theoretical ecology for marine microbes in the Baltic Sea and Pacific Ocean to implications for marine evolutionary biology

Markus Lindh

Marine bacteria regulate global cycles of elements essential to life and respond rapidly to environmental change. Yet, the ecological factors that determine distribution and activity patterns of microbial populations across different spatial scales and environmental gradients remain basically unconstrained. Our metapopulation model-based analyses show that dispersal-driven processes contribute to structuring the biogeography of marine microorganisms from small to large geographical areas. Discovery of bimodal distribution patterns pinpointed satellite microbial populations with highly restricted ranges and defined abundant core populations widely distributed in coherence with environmental conditions. Our results indicate that application of metapopulation models on microbial community structure may allow the definition of biogeographic regions critical for interpreting the outcome of future ocean changes. Ultimately, ecological and evolutionary studies, using e.g. "-omics" approaches, on marine microbial communities could benefit from first understanding metapopulation dynamics through identification of core and satellite populations as well as distinct microbial biomes.

Adaptive evolution to warming in the common diatom Skeletonema marinoi

Kai Lohbeck, Olga Kourtchenko, Mats Töpel, Kjell Nordberg, Ardo Robijn, Anke Kremp, and Anna Godhe

Ocean warming will likely affect many marine organisms and can result in severe consequences for ecosystem functioning and biogeochemical cycles. Thus, a profound understanding of evolutionary processes will be indispensable for reliably predicting biological responses to ocean change and is of pivotal relevance, not only to science, but also to policy makers and society. Our present understanding of the biological consequences of ocean warming is mostly based on short-term experiments. In contrast, very little is known about the potential for evolutionary adaptation to rising temperatures. Fast reproducing planktonic organisms, such as phytoplankton, are particularly prone to respond to environmental change via evolutionary adaptation. The few laboratory selection experiments that have addressed rapid evolutionary adaptation in phytoplankton to date suggest that adaptation can mitigate negative effects of climate change. However, how relevant adaptive responses in the laboratory will be under field conditions remains to be resolved. To tackle this question, we use strains of the common diatom Skeletonema marinoi revived from resting stages embedded in the sediments of Hästholmsfjärden in Finland. This site is affected by cooling water discharges from a nuclear power plant that have increased seawater temperatures for decades and offer a promising setting to investigate evolutionary adaptation to warming in a natural phytoplankton population. Diatom cultures are grown in the laboratory and assayed under different temperatures to investigate potential consequences of the warm water influx compared to populations from a non-affected control site. Our results can help to assess the potential for evolutionary adaptation to global warming in natural phytoplankton populations and further bridge the gap between adaptive evolution observed in the laboratory and adaptation to warming in the wild.

High-throughput phenomics for identifying synergistic chemical interactions in the marine yeast Debaryomyces hansenii and the baker’s yeast Saccharomyces cerevisiae

Vaskar Mukherjee1, Thomas Backhaus2, Anders Blomberg1
1 Department of Marine Sciences, University of Gothenburg
2 Department of Biological and Environmental Sciences, University of Gothenburg

Prevalence of mixtures of synthetic and natural chemicals in the environment is a growing concern for public health and environmental effects. Currently, most chemical legislations around the world are based on the risk assessments carried out on individual substances and theoretical estimates of combination effect. However, exposure to multicomponent mixtures may stimulate unpredicted overall toxic response due to synergistic interactions in chemical mixtures, which in turn induce unintended adverse impacts. Therefore, it is increasingly important to develop a high-throughput experimental approach to identify and to characterize synergy dose-responses and to upgrade the current modeling approaches in order to obtain more reliable risk assessment. In our project, we are investigating the frequency of synergistic toxicity in mixtures of chemicals by employing high-throughput yeast phenomics involving high-resolution phenotyping techniques recently developed in our laboratory. Primarily we are focusing on 9 compounds with a known specific mode of action and 21 other compounds that are declared as priority hazardous substances by European Commission. The baker’s/brewer’s yeast Saccharomyces cerevisiae and the marine yeast Debaryomyces hansenii is used in this study as the model organisms to determine the independent single-substance and the synergy dose-responses of the chemicals. Thus, we will examine organisms at large evolutionary distance hopeing to identify generic response of relevance vast arrays of organisms. Our early results clearly suggest that both synergistic and antagonistic relationships exist among the tested chemicals and some of these relationships are concentration dependent.

Swedish Society for Virology: Engagement in marina and environmental Virology.

Sigvard Olofsson
Dept of Biomedicin, Sahlgrenska Academy, University of Gothenburg

Swedish Society for Virology gathers virologists of all areas of and  aspects on Virology, including Medical, Animal, Plant and bacterial Viruses. The general assembly of the Society takes place at the annual symposium on Virology, taking place every year week 34 in Smögen. In 2017 the 14th Smögen Summer Symposium on Virology will be arranged. In connection with and immediately preceding the symposium PhD courses are arranged at the venue in Smögen in different sub disciplines  of Virology. The symposia as well as the PhD courses are very popular and heavily overbooked. In 2017 emphasis will be put on Environmental and Marine Virology both with respect to the General Symposium and the PhD Course, the latter aimed at ”Marine and Molecular Virology”. The Society, its interest in Marine and Environmental Virology, the Symposium and the PhD course will be presented.

Using bioinformatics to investigate the Skeletonema marinoi microbiome

Matt Pinder
Dept Marine Sciences, University of Gothenburg

The marine diatom Skeletonema marinoi has been found to harbour a diverse microbiome. Axenic growth of S. marinoi has proven difficult, leading us to believe that these bacteria are hugely important to the diatom; however, the individual importance of these associated bacterial species has not yet been determined. To that end, several bioinformatics tools have been used to both taxonomically identify the bacteria, and to predict their role in the relationship with S. marinoi.
These analyses have identified multiple potential roles that the bacteria may play, including vitamin and growth hormone production which benefit S. marinoi, with many of the bacteria apparently able to utilise diatom-produced carbon/sulphur sources in return. Other genes suggestive of a symbiotic or parasitic relationship were also identified in the bacteria, including genes related to quorum sensing (coordination of gene expression based on bacterial cell density).

These predictions show that, through the use of bioinformatics tools, a lot of information can be gained about the relationship between diatoms and bacteria – in particular relating to the model organism Skeletonema marinoi – demonstrating the merits of such an approach. The results can also help to inform future experimental designs, such as for testing hypotheses regarding the roles of these bacteria.

On the ecology of marine bacteria: some insights from field studies and experiments

Jarone Pinhassi
Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Linnaeus University, Sweden

Cross-feeding of fixed nitrogen from prokaryotes to eukaryotes within a plankton community

Helle Ploug
Dept of Marine Sciences, University of Gothenburg,
e-mail: Helle.Ploug@marine.gu.se

The quantitative role of the N2-fixing, colony-forming cyanobacterium, Aphanizomenon sp., with respect to N2-fixation and transfer of nitrogen within the phytoplankton community in the Baltic Sea was investigated by using stable isotope tracers combined with secondary ion mass spectrometry (SIMS). It is shown that Aphanizomenon sp. contribute > 50% of total N2-fixation through the year in the Baltic Sea. About half of the recently fixed N is released as NH4+ from Aphanizomenon sp. both during its growth in the early summer and late summer and quickly transferred to the prokaryotic and eukaryotic plankton. Recently fixed 15N2 by Aphanizomenon was tracked in diatoms and in zooplankton that form the basis of the classical food web in the Baltic Sea. Hence, N2-fixation and NH4+ release by Aphanizomenon support the N-limited primary production of other members of the plankton community through the summer and not only during the decay of cyanobacterial blooms which are remineralized by heterotrophic bacteria during early autumn.

Ecology of the seaweed holobiont

Peter Steinberg
Sydney Institute of Marine Science, University of New South Wales Australia and Nanyang Technological University, Singapore

Increasingly, macro-organisms ranging from corals to trees to humans are being viewed as holobionts, systems comprised of a host and their associated microbial community (or microbiomes). We have studied the ecology of seaweed holobionts for a number of years, and I will focus on three aspects of that work. First, what is the etiology, epidemiology and impact of disease in seaweeds, and how do we understand that in the context of environmental change and the broader ecology of these coastal systems? Second, what are the underlying community dynamics of the microbiomes themselves, in systems where diversity may exceed thousands of “species”. Third, I will use these examples to explore a number of broader themes in microbial ecology and evolution, including: the challenge of Koch’s postulates as a paradigm for disease in natural systems; differences between microbiomes of benthic holobionts and oceanographic microbial communities, and; attempts to reconcile the approaches of environmental microbiology vs. those of eukaryotic marine ecology for a fuller understanding of marine holobionts.

High-throughput investigation of marine microbial interactions –insights from a genome comparison perspective
Luca Zoccarato1
and Sher D2, Grossart H-P1.

1Department Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany; 2Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.

Presenting author’s e-mail address: zoccarato@igb-berlin.de

Marine microbes are responsible for turnover of half of the net global primary production in aquatic systems. This is the result of a close coupling between autotrophic production and heterotrophic consumption, and the balance between these two processes is critical in shaping the fate of each mole of fixed CO2. Most of this interplay occurs at the microscale level, and to unveil how microorganisms affect each other via cell-to-cell interactions will enhance our understanding on biogeochemical processes from the micro- to the global scale. To date, there are several exciting evidences on how heterotrophic bacteria can interact with diatoms or cyanobacteria, but most of these studies used specific model systems with a much lower complexity than natural systems. In order to widen our perspective on such complex interlinkages, our Human Frontiers Science Project (HFSP) aims to test in co-culture a large library of genome-sequenced, marine heteroptrophic bacteria against some of the most representative primary producers of the global oceans (i.e. the cyanobacteria Prochlorococcus and Synechococcus and the diatoms Thalassiosira rotula and Skeletonema marinoi). Our aim is to describe and quantify how different combinations between the diatom host and the associated heterotrophic bacteria are interacting with increasing complexity using a tightly integrated combination of laboratory analysis and genome scale modeling. We are now finalizing the list of heterotrophic bacteria strains that are ecologically relevant but also representative for the natural bacterial diversity in terms of functionality and phylogeny. Bacteria candidates are identified by collecting literature information and through a comparative analysis of their whole genomes, which highlights the presence of functional patterns among genomes of strains of different phylogenetic groups. Most of the genome functional clusters correlate with their phylogenetic/evolutionary distance. However, some functional clusters showed quite some phylogenetic heterogeneity that might point to a possible functional convergence of distantly related organism. Therefore, we propose that the phylogenetic identity of bacteria strains does not always allow for conclusions on their functional role.


Page Manager: Eva Marie Rödström|Last update: 4/21/2017

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