Vores planet er beboet af et enormt antal mikroorganismer. Deres aktivitet er essentiel for det globale stofkredsløb og for sundhed og funktion af økosystemer og organismer – fra planter til mennesker. Dertil kommer, at vi udnytter mikrobielle processer og produkter i en lang række industrielle processer så som spildevandsrensning, produktion af energi, fødevareproduktion og bioteknologi.
På Institut for Biologi undersøger vi de mekanistiske detaljer bag mikrobielle processer i naturlige og i menneskeskabte systemer, og vi studerer de mikroorganismer, der driver dem. Denne viden er fundamental for at forstå, hvordan stofkredsløbet påvirkes af ydre påvirkninger som for eksempel klimatiske forandringer, eller hvordan vi kan påvirke mikrobielle processer til at fungere til vores fordel i forbindelse med, eksempelvis, kvælstoffjernelse under spildevandsrensning eller til begrænsning af produktion af svovlbrinte i kloaker og i oliefelter.
Vores forskning spænder over alle niveauer af biologisk organisation fra cellulære processer, via mikrobielle samfund og hele økosystemer, til det globale stofkredsløb.
Our research group aims to investigate evolutionary ecology and genetics of group living, cooperation and mating systems using spiders as study systems. Additionally, we are interested in understanding the genomic consequences of sociality and inbreeding mating systems, and genetic and non-genetic processes involved in adaptation to different environments.
Our research focuses on the spider genus Stegodyphus (family Eresidae) that contains both social and subsocial (temporarily social) species, which makes it ideal for comparative studies. The social spiders are unique among group living animals, as the transition to permanent sociality is associated with regular inbreeding and highly female-biased sex ratios. Additionally, social spiders cooperate in all colony tasks and show allomaternal brood care including self-sacrifice.
Left: Colonies of the social spider Stegodyphus dumicola in South Africa, May 2012. The dense silk nests may contain several hundred spiders and are often interconnected with prey capture webs. Photo by: V. Settepani. Right: Stegodyphus lineatus, matriphagy.Photo by: T. Bilde.
Our research aims to understand 1) the ecology and evolution of sociality, 2) reproductive division of labour and conflict resolution, and 3) population genomic consequences of inbreeding 4) non-genetic processes involved in adaptation.
Many of our projects are interdisciplinary and involves collaboration with colleagues with expertise in different fields e.g. zoology (Prof Yael Lubin, Ben Gurion University; Prof Gabriele Uhl, University of Greifswald; Dr. Tharina Bird, Natural ural History Museum of Windhoek (Namibia) and Botswana International University of Science and Technology), microbiology (Prof Andreas Schramm), bioinformatics (Prof Mikkel Schierup, BiRC), chemistry and metabolomics (Prof Thomas Vosegaard, inSPIN and iNANO; Prof Michael Lalk, University of Greifswald). We perform field work in South Africa, Namibia, Botswana, India and Israel.
Additionally, we study the evolution of polyandrous mating systems and the evolution of alternative male mating strategies in the nursery web spider Pisaura mirabilis*. This work is done in collaboration with Ass. Prof. Cristina Tuni, University of Munich, and field work in Germany, Italy, UK and Denmark.
1) Ecological genomics of inbreeding: comparative studies of inbreeding mating systems in non-model animal populations (funded by the European Research Council)
We are interested in integrating ecological and evolutionary research in order to expand knowledge on the evolutionary ecology of inbreeding in wild animal populations. We perform comparative population studies on the consequences of inbreeding in Stegodyphus, a genus of spiders including three independently evolved inbreeding social species as well as outcrossing sister species. We investigate the consequences of sociality and inbreeding for population genetic structure, genome-wide genetic diversity, molecular evolution and evolution of life history traits.
Left: The subsocial Stegodyphus lineatus eating a fly in our spider lab, Aarhus, August 2010. Right: Individuals of the social spider Stegodyphus sarasinorum foraging on an ant. India, October 2010. Photos by: V. Settepani
2) Non-genetic processes involved in adaptation
Evolutionary models predict that response to environmental change occur by selection on standing genetic variation and new mutations, but it is becoming apparent that adaptation is more complex than so far realised, calling for integration of non-genetic mechanisms in our understanding of adaption, such as microbial symbionts or epigenetic changes.
Social spiders are have a wide ecological range characterized by very different habitat despite being highly inbred and showing extremely low species-wide genetic variation. We are therefore interested in examining mechanisms other than genetic variation involved in their adaptation:
- The influence of epigenetic modifications in the response to environmental change (funded by the Danish Council for Independent research):
Epigenetic modifications contribute to phenotypic variation by modifying gene expression without altering the underlying genetic code, and may therefore facilitate rapid adaptation to environmental change. We are interested in linking epigenetic modifications to the expression of phenotypic traits and individual performance along a temperature gradient, to identify mechanisms that provide adaptive benefits in specific environments.
- The influence of the microbiome in the response to environmental change:
All animals live in close association with complex microbial communities, which often contribute important function to the host phenotype. We will investigate the influence that bacterial symbionts have on local adaptation in populations of inbred social Stegodyphus in different environments. Bacterial symbionts often contribute important functions to the host phenotype and we aim to determine the spider microbiome, and to identify and link key symbionts that contribute to enhance host performance.
Map of the mean annual temperature in Namibia, Botswana and South Africa, were we carry out our field works. Map made by V. Settepani with data from the AfrClim database.
3) Discovery and characterization of novel antimicrobials (funded by Novo Nordisk Foundation’s Interdisciplinary Synergy Programme)
Social spiders are highly inbred and show extremely low genetic variation, also in immune genes. Combined with an elevated risk of pathogen transfer among individuals living in close proximity, they should be highly susceptible to pathogens and disease transmission. Nevertheless, social spiders are evolutionarily and ecologically very successful, leading us to hypothesize that microbial symbionts must be essential in their protection against pathogens. We are investigating the potential of host symbionts for producing protective and novel antimicrobial compounds that provide protection against pathogens.
The team involved in the Novo Nordisk Foundation’s Interdisciplinary Synergy Programme. From left to right: Dr Marie Lund, Dr Jesper Bechsgaard, PhD Mette Marie Busck, Prof Thomas Vosegaard, Prof Trine Bilde, Prof Andreas Schramm, Dr Virginia Settepani, Prof Michael Lalk.
4) Evolution of social behaviour: social structure and task differentiation
Division of reproductive and non-reproductive tasks in cooperative societies is expected to reduce conflict and optimize group performance. Social spiders cooperate in all colony tasks, only some of the females in a colony reproduce while the non-reproducers become helpers. All females in the colony, reproducers and non-reproducers, actively provide extended maternal care including self-sacrifice (spiderlings consume adult females). This society structure is perfect for investigating task differentiation in reproductive and non-reproductive roles. We are interested in understanding the social structure of the spider’s colonies and the mechanisms underlying reproduction division of labour and differential participation in non-reproductive tasks such as foraging and web maintenance.
Left: A cluster of social Stegodyphus sarasinorum spiders individually marked for task differentiation studies, India, November 2012. Right: Individuals of the social spider Stegodyphus mimosarum foraging on a fly. Spiderlab Aarhus, March 2014. Photos by: V. Settepani.
5) The role of sexual selection on alternative male mating strategies (funded by the Danish Council for Independent research)
The main goal of this study is to understand how sexual selection and male-female co-evolution drives the evolution of alternative male mating strategies. Our model system is the nursery web spider Pisaura mirabilis, where male spiders employ alternative mating strategies (death feigning and worthless nuptial gifts). We are investigating whether alternative strategies in natural populations are maintained by variation in prey availability, female mate choice, and the intensity of sexual selection.
Right: Adult female of the nursery web spider Pisaura mirabilis Germany, July 2009. Photo by: V. Settepani. Left: An adult male Pisaura mirabilis (in the bottom)offers a prey to the female as a nuptial gift to initiate mating. Photo by: Allan Lau.
* For more information on this project click here: https://bio.au.dk/en/research/research-areas/geneticsecologyandevolution/research-profile/trine-bilde-ecology-genomics-and-adaptation/evolutionary-stable-strategies/
Hans Brix's ekspertise ligger indenfor områderne botanisk økologi og økofysiologi med særlig fokus på vådområder, søer og vandløb. Fokus er på invasive planter og deres økofysiologi. Forskningen omfatter studier på økosystem niveau, fx emission af drivhusgasser fra vådområder, og studier på individniveau, fx intern gastransport og udskillelse af ilt fra rødder samt interaktionen med det omgivende miljø. Anvendte aspekter af forskningen er rensning af spildevand i plantebaserede renseanlæg. Hans Brix har samarbejder med mange danske og udenlandske virksomheder om rensning af spildevand in konstruerede vådområder.
My research revolves around two foci points: Aeromicrobiology and Astrobiology. The first is on the role of Ice-forming bacteria in processes in Earth atmosphere and the second is on the role of wind-driven processes in Martian surface chemistry.
Thus, I am studying the structure and function of an ice forming protein produced by the plant pathogen Pseudomonas syringae. It is the aim of the studies to find out to what extend this and related bacterial species influence processes in the atmosphere such as cloud and rain formation; processes of relevance for weather and climate. With respect to Mars, my research goal is contributing to a better understanding of the processes that determine the chemical conditions of the Martian surface and their influence of biomarker degradation and the discovery of life.
Read more: Bacteria in the atmosphere
In aeromicrobiology, we use various methods depending on the questions that we are addressing. As an example, we use a modified vacuum cleaner to take air samples to investigate the microbial air community. We use molecular methods in combination with flow cytometry and electron microscopy to elucidate the structure and function of proteins that promote the formation of ice in clouds. In astrobiology, we use spectroscopic methods to study processes that lead to the high reactivity of minerals as we find them on Mars and investigate their participation in aerosol-gas chemistry.
All my projects are interdisciplinary and are altogether a group effort. In aerobiology, we collaborate with AU colleagues from chemistry, molecular biology and engineering. Internationally, we closely collaborate with e. g. climate modelers from Sweden, atmospheric physicists from Germany and microbial ecologists from Austria. The astrobiology group, includes geologist, physicists and chemists from Aarhus University. We collaborated with e. g. planetary scientists from Germany, geologists from France and geochemists from Spain.
Read more: Aeromicrobiology Research Group
I study the microorganisms and element cycles in the seabed, in particular sulfate reduction, methane cycling and the degradation of organic matter. The goal is to understand the pathways of these biogeochemical processes and how microbiology and geochemistry control their rates.
We recently discovered a cryptic methane cycle in the seabed, whereby a group of archaea are apparently able to both produce and oxidize methane in the same sediment at the same time. I now study how these concurrent processes are energetically controlled and whether extracellular electron exchange with conducting minerals enables a reversal of the metabolic pathway.
We use experimental radiotracer techniques and stable isotope dilution methods to measure microbial metabolic rates. We compare these rates to the community size of the responsible microorganisms to understand how the metabolic activity per cell is regulated in the seabed.
In our current study of cryptic methane cycling, I am associated with the DNRF Center for Electromicrobiology and collaborate with the University of Southern Denmark and the Helmholtz Centre for Environmental Research. I also collaborate with NASA-Ames Research Center, Harvard University and the University of Colorado to study how the global energy flux controls the carrying capacity of the biosphere on Earth.
I am an associate professor in molecular geomicrobiology. My research overall focuses on understanding the ecology and evolution of microorganisms inhabiting the seabed as well as engineered systems. My expertise bridges the use of more basic molecular tools with omics and bioinformatics approaches which I integrate with microbial physiology and biogeochemical approaches.
Geomicrobiology
The microorganisms present the seabed constitute up to one third of global living biomass, they key players in the global carbon and sulfur cycles and thus affect both ocean and atmospheric chemistry and Earth´s climate. However, the subsurface seabed is among the least explored environments on our planet and the identities, evolution and lifestyles of the microorganism populating this vast microbial ecosystem remain poorly understood.
Active projects
Teaching
I teach the following courses at Department of Biology
My main research interest is to use advanced sensing tools to answer questions in biological, environmental and medical research. Either I use available sensors to address biological questions, or if the needed tools are not available, I develop them.
From soil to marine biofilms, bacteria drive the cycling of nutrients in the environment. The chemical conditions present determine the processes. With optical sensors I can make those chemical conditions visible in 2D.
I work on developing and using both optical and electrochemical sensors. A main difference to other labs around the world is that we develop sensors to be functional in complex natural environments and to sense at a high spatial (<100µm) and temporal (<5sec) resolution.
As a trained chemist working at a Biology department, I collaborate across disciplines every day. I have a strong national and international research network.
Geomicrobiology in the deep marine biosphere
Chemical composition of organic matter and controls of bacterial communities in anoxic marine sediment
Microbial reworking of organic matter in surface sediment
Dispersal of bacterial endospores
Quantification of endospores, microbial growth and necromass turnover in deep sub-seafloor sediment
Collaboration with members of the Center for Geomicrobiology, AU, and international colleagues
I investigate the main factors that regulate macronutrients cycling in aquatic systems. I am particularly fascinated by the activity of electro-active bacteria, their geochemical impact, diversity and their potential technological application.
By mediating electric currents, filamentous (“cable”) bacteria can significantly alter geochemical reactions in sediments. In an EU-funded project, I explored how cable bacteria impact benthic nitrogen cycling and their distribution and diversity in the Baltic Sea.
I apply a broad range of sensing and isotopic techniques.
Our results show that cable bacteria stimulate nitrate reduction to ammonium, thereby contributing to the recycling of nitrogen in aquatic systems.
We also demonstrated that electrically connecting the surface sediment with the deeper layers by means of biological or inert conductors helps to accelerate hydrocarbon degradation.
I maintain collaborations with researchers in the fields of marine and freshwater biogeochemistry, microbiology, aquatic ecology and biotechnology. My network includes researchers from Sweden, Belgium, Italy, and Germany.
Min forskningsinteresse er nu kabelbakterier i særdeleshed og elektromikrobiologi i almindelighed. Se mer og følg os på Center for Elektromikrobiologi
Most significant contributions:
Prof. Rysgaard has contributed significantly to fundamental understanding how, where, and when settling organic matter is degraded in temperate and arctic sediments. The work includes biogeochemical pathways and the cycling of redox elements in marine sediments and sea ice. New knowledge has been achieved on degradation pathways in various sediments, including those inhabited by bioturbating benthic animals and/or colonized by microalgae/macroalgae. His scientific achievements count initiating and raising funds for comprehensive marine system studies in the Arctic. These studies still continue and comprise several sub-research projects and two long-term monitoring programs in Greenland. They are the most comprehensive decadal studies of carbon and nutrient cycles ever made in the Arctic. His is behind many new discoveries from physical to chemical and biological processes related to sea ice formation and melt and how sea ice affects greenhouse-gas exchange between the atmosphere and ocean. Another road of his achievements relates to ocean-glacier interactions. Some of his recent discoveries is a new heat sources for glacial melt in fjords in contact with the Greenland ice sheet, and that melt water plumes in front of calving marine glaciers greatly affects physical, chemical and biological processes in fjords and coastal waters.
Andreas Schramm's research interests are microbial ecophysiology and evolution, for example of microbe-host interactions, cable bacteria, and microbes involved in aquatic nitrogen cycling and sediment biogeochemistry. His current research focus is on the physiology and interactions of electrically conductive cable bacteria, the microbiomes of social spiders, and other invertebrate-microbe symbioses.
I work on photosynthesis, the basis of almost all life on earth, arguably the most important process in biology. I’ve studied photosynthesis in all kinds of aquatic plants, from the tiniest microscopic phytoplankton right up to three metre-tall mangrove trees.
My two current research areas are (i) photosynthesis in Arctic sea ice algae; and (ii) photosynthetic carbon assimilation in wetland plants and its importance for ensuring that restored wetlands are net sinks for greenhouse gases, offsetting climate change.
Measuring photosynthesis in sea ice algae is very difficult, and we have been studying them using advanced chlorophyll fluorescence methods. Our work in wetlands uses special high-resolution greenhouse gas analysers: Read more: * | Carlsbergfondet
Polar science projects are always interdisciplinary and international, and in the Arctic we collaborate with oceanographers, microbiologists, physicists and molecular biologists from New Zealand, Australia, Germany and Norway. In our wetland science, we have been key players in several international, interdisciplinary projects. Read more: MoorWissen | Paludiculture| Projects | Cinderella
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