Marine microbiology

The research group Marine microbiology carries out research on the biodiversity, ecology, physiology, genomics and genetics of marine bacteria.

Our research

The research group is a part of Linnaeus University Centre for Ecology and Evolution in Micobial model Systems.

Our research includes the study of species composition in bacterial communities and of the significance of bacteria in marine ecosystems. This includes research into the role of bacteria in the cycling of organic and inorganic nutrients, and in the energy fluxes in the sea. Particular attention is given to bacterial light energy harvesting through rhodopsin photoproteins.

Bacteria make up most of the living biomass in our biosphere and their activities drive biogeochemical cycles of all elements essential to life. For example, about 25% of the carbon fixed by photosynthesis on Earth is channeled through bacteria in the marine water column. While the recent decade has brought insights into the identity and functional diversity of bacterioplankton species, the understanding of factors regulating bacterial activities, and thereby the resilience of bacterial ecosystem function towards environmental change, is still scarce. Hence, pertinent current questions include: how do specific bacteria carry out different biogeochemical processes, i.e. what molecular mechanisms are involved? - and how are these activities regulated? How does rhodopsin light energy harvesting influence the ecology of marine bacteria?

Our research projects in marine microbiology and molecular biology are focused on complementary aspects of marine microbial ecology.

Research themes

Research approaches

We use a series of established and state-of-the-art methods in microbial ecology to determine the activity of bacteria in the water column. This is linked with genetic analyses at the DNA and RNA level (genomics and transcriptomics, respectively) to investigate the molecular mechanisms that determine the ecological function and success of different bacteria in the marine environment. Moreover, we use comparative proteome analysis on natural bacterial assemblage and on bacterial isolates to examine similarities and differences in metabolism and physiology of genome-sequenced and representative marine bacteria under various growth limiting conditions.

Staff

Gruppbild

Field studies/expeditions

BLUEPRINT Mesocosm experiment in Kalmar, May 2016

The overreaching aim of the mesocosm experiment was to investigate adjustments in bacterial community composition and activities caused by specific stressors such as riverine input, phytoplankton blooms and toxic cyanobacteria in the Baltic Sea. Water was collected from the LMO station east of Öland in the Baltic Sea and divided into separate mesocosms with 5 different treatments. The 300 liter containers were placed in a climate room with fixed light intensities and temperature, after which nutrient conditions (stressors) were adjusted. The resulting phytoplankton blooms and the bacterial responses were monitored daily (e.g. for multiple rate measurements and genomics and metatranscriptomics). Ongoing work includes determining the changes in the bacterial community composition during the experiment and analyses of bacterial gene expression patters.

ENVISION cruises 2016, Atlantic, NW Spain

During 2016 we participated in 3 cruises across a cost-offshore gradient off Vigo on the Atlantic coast of NW Spain. This was the first part of the 3-year project "ElucidatiNg the role of B-VItamins in microbial plankton community structure, activity and succesSION in a coastal upwelling system (ENVISION)" with Prof. Eva Teira, University of Vigo, Spain, as project leader. Our research group's primary objective during the 3 ENVISION cruises, carried out at different seasons, was to collect water samples for subsequent high-throughput sequencing of messenger RNA transcripts (mRNA), derived from the complex natural microbial communities (i.e. for metatranscriptomics). These samples have been sequenced on Illummina HiSeq 2500 instruments at the Swedish SciLifeLab, Stockholm - the national center for molecular biosciences. To a large degree we participated in the sampling of in situ stations, particularly the surface layer. We also helped our Spanish colleagues in setting up complementary mesocosm and enrichment experiments at different stations and in extracting and measuring chlorophyll samples, and assisted in the daily preparation work. It has been an extraordinary experience to join the cruises aboard the R/V Ramón Margalef, resolving challenges beyond the bounds of research in a laboratory. We are now looking forward to data analyses and eventual follow-up studies. 

International collaboration

  • 4 years research project (2016-2019): "Bacterial carbon cycling in the sea: quantifying the influence of proteorhodopsin phototrophy on organic matter degradation" (diarienr. 2015-04254). Funded by the Swedish Research Council VR. In collaboration with Professor Patricia Medeiros, Marine Sciences, University of Georgia, Athens, US.
  • Genome analysis of marine bacterioplankton: Dr. José M. González, Universidad de La Laguna, Tenerife, Spain and Prof. Carlos Pedrós-Alió, ICM-CMIMA (CSIC), Barcelona.
  • Phylogenomics of marine Bacteroidetes: Prof. Mary Ann Moran and Dr. Haiwei Luo, Department of Marine Sciences, University of Georgia, USA.
  • Diversity and function of marine bacteria: Dr. Josep M. Gasol, Institut de Ciencies del Mar-CMIMA (CSIC), Barcelona.
  • BONUS project BLUEPRINT Prof. Lasse Riemann, Dept. of Biology, University of Copenhagen, Denmark, Prof. Klaus Jürgens, Leibniz Institute of Baltic Sea Research, Rostock-Warnemünde. Germany; and 4 more scientists.
  • Assessing bacterioplankton ecosystem function through genomics, transcriptomics and proteomics of Baltic Sea bacterioplankton: Dr. Anders F. Andersson and Dr. Janne Lehtiö, SciLifeLab, Stockholm. Analysis of phytoplankton interactions with omics: Rachel Foster, Massimo Pernice Stockholm University
  • ISOMICS - Interaction between synthetic organic pollutants and the microbial pump in coastal seawaters: Maria Vila-Costa, IDAEA - CSIC, Barcelona, Spain.