The aim of our research is to study energy production in microorganisms. We use an integrative approach with a combination of molecular biology, biochemistry and ecophysiology.

Anita sellstedt 1150Hydrogen metabolism of Frankia
The nitrogen-fixing filamentous actinobacteria of the genus Frankia form root nodules in symbioses with many woody trees and shrubs. Nitrogen fixation by actinorhizal plants may contribute as much as a quarter of the total biologically fixed nitrogen globally in terrestrial ecosystems each year.In addition, actinorhiza are major sources of new soil nitrogen in many different biomes.
The most important recent achievement in the Frankia research field is undoubtedly the sequencing of three Frankia genomes.We were able to show that there are large differences in the genome sizes. Frankia EANpec1 was found to have the largest genome with 9.0 Megabases (Mb), while Frankia AC- N14a had an intermediate size (7.5 Mb) and Frankia HFPCcI3 was the smallest at 5.4 Mb.These numbers were correlated with geographical origin, host plant distribution and repeated sequences, such as IS. Our findings open up a new era in Frankia research, yielding possibilities to explore the molecular biology of Frankia and to utilize its traits, e.g. nitrogen fixation.
An inevitable source of energy-inefficiency in the nitro- gen-fixation process is the evolution of hydrogen; as much as 25% of the in vitro electron flow through nitrogenase goes to hydrogen evolution, while in vivo these losses are much higher. Some nitrogen-fixing systems have dealt with this problem of energy loss through an enzyme, called uptake hydrogenase, which is very common in Frankia.

anita_1 anita_2
Light micrograph of the bacterium Frankia showing vesicles. Light micrograph of our isolate of Chalara parvispora

Ethanol production
We are interested in developing ethanol production from cel- lulose-based biomass.We have shown in a batch fermentation study that a fungal mix could produce 24 g L-1 ethanol using pulp waste as substrate.The fungal mix was able to grow on xylose, hemicellulose and cellulose. In addition, we were able to identify the fungi mix using PCR-amplification of DNA and sequencing as Chalara parvispora andTrametes hirsuta/T.versicolor. In a reconstitution study,the identified fungi were shown to pro- duce equal amounts of ethanol as the fungi mix. In addition, it was shown that C. parvispora could produce ethanol from xylose.
The study shows that refining biomass by ethanol production from pulp waste, a lignocellulose material, can be increased by adding C. parvispora and T. versicolor, which is of great economic significance for energy production.
sweden_greySvensk sammanfattnin

Publications list

  1. Photo-electrochemical hydrogen production from neutral phosphate buffer and seawater using micro-structured p-Si photo-electrodes functionalized by solution-based methods
    SUSTAINABLE ENERGY & FUELS 2018, 2(19):2215-2223
  2. Mixotrophic and heterotrophic production of lipids and carbohydrates by a locally isolated microalga using wastewater as a growth medium
    Bioresour Technol. 2018; 257:260-265
  3. Adaptability of Trametes versicolor to the lignocellulosic inhibitors furfural, HMF, phenol and levulinic acid during ethanol fermentation
    BIOMASS & BIOENERGY 2016, 90:95-100
  4. Genome Sequence of the Atypical Symbiotic Frankia R43 Strain, a Nitrogen-Fixing and Hydrogen-Producing Actinobacterium
    Genome Announc. 2015, 3(6)
  5. Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose
    Plant Biotechnol J. 2015, 14 (1):387-397
  6. Biomass-Based Energy Production
    in Introduction to Chemicals from Biomass, Second Edition (eds J. Clark and F. Deswarte) (2015), John Wiley & Sons, Ltd, Chichester, UK
  7. Structural and gene expression analyses of uptake hydrogenases and other proteins involved in nitrogenase protection in Frankia
    Journal of Biosciences, 2013; 38(4):703-712

  8. Aspects of nitrogen fixing Actinobacteria, in particular free-living and symbiotic Frankia
    FEMS Microbiol Lett. 2013 ;342 (2):179-186
  9. Kudahettige RL, Holmgren M, Imerzel P, Sellstedt A
    Characterization of bioethanol production from hexoses and xylose by the white rot fungus Trametes versicolor
    Bioenergy Research:
    Volume 5(2), (2012), 277-285
  10. Kosawang C, Kudahettige RL, Resman L, Sellstedt A
    Hydrogen yield from a hydrogenase in Frankia R43 at different levels of the carbon source propionate
    Journal of Environmental Management: 2011, Epub ahead of print
  11. Leul M, Normand P, Sellstedt A
    The phylogeny of uptake hydrogenases in Frankia
    International Microbiology: 2009 12:23-28
  12. Zackrisson O, DeLuca TH, Gentili F, Sellstedt A, Jäderlund A
    Nitrogen fixation in mixed Hylocomium splendens moss communities
    Oecologia: 2009 160:309-319
  13. Holmgren M, Sellstedt A
    Identification of white-rot and soft-rot fungi increasing ethanol production from spent sulfite liquor in co-culture with Saccharomyces cerevisiae
    Journal of Applied Microbiology: 2008 105:134-140
  14. Leul M, Normand P, Sellstedt A
    The organization, regulation and phylogeny of uptake hydrogenase genes in Frankia

    Physiologia Plantarum: 2007 130:464-470
  15. Santos CL, Vieira J, Sellstedt A, Normand P, Moradas-Ferreira P, Tavares F
    Modulation of Frankia alni ACN14a oxidative stress response: activity, expression and phylogeny of catalases
    Physiologia Plantarum: 2007 130:454-463
  16. Tavares F, Santos CL, Sellstedt A
    Reactive oxygen species in legume and actinorhizal nitrogen-fixing symbioses: the microsymbiont's responses to an unfriendly reception
    Physiologia Plantarum: 2007 130:344-356
  17. Sellstedt A, Normand P, Dawson J
    Frankia - the friendly bacteria - infecting actinorhizal plants
    Physiologia Plantarum: 2007 130:315-317
  18. DeLuca TH, Zackrisson O, Gentili F, Sellstedt A, Nilsson M-C
    Ecosystem controls on nitrogen fixation in boreal feather moss communities
    Oecologia: 2007 152:121-130
  19. Normand P, Lapierre P, Tisa LS, Gogarten JP, ..., Sellstedt A, Tavares F, et al
    Genome characeristics of facultatively symbiotic Frankia sp. strains reflect host range and host plant biogeography
    Genome Research 2007 17:7-15
  20. Mohapatra A, Leul M, Sandstrom G, Sellstedt A
    Occurrence and characterisation of the hydrogen-evolving enzyme in Frankia sp
    International Journal Of Hydrogen Energy: 2006 31:1445-1451
  21. Nitrogen fixation and biomass production in symbiosis between Alnus incana and Frankia strains with differrent hydrogen metabolism
    Physiol. Plant. 2006; 66(1):99-107
  22. Leul M, Mohapatra A, Sellstedt A
    Biodiversity of hydrogenases in Frankia
    Curr Microbiol: 2005 50:17-23
  23. Stahl L, Hogberg P, Sellstedt A, Buresh RJ
    Measuring nitrogen fixation by Sesbania sesban planted fallows using N-15 tracer technique in Kenya
    Agroforestry Systems: 2005 65:67-79
  24. Leul M, Mattsson U, Sellstedt A
    Molecular characterization of uptake hydrogenase in Frankia
    Biochem Soc Trans: 2005 33:64-66
  25. Gentili F, Nilsson MC, Zackrisson O, DeLuca TH, Sellstedt A
    Physiological and molecular diversity of feather moss associative N-2-fixing cyanobacteria
    Journal Of Experimental Botany: 2005 56:3121-3127
  26. Mohapatra A, Leul M, Mattsson U, Sellstedt A
    A hydrogen-evolving enzyme is present in Frankia sp. R43
    FEMS Microbiol Lett: 2004 236:235-240
  27. Zackrisson O, DeLuca TH, Nilsson MC, Sellstedt A, Berglund LM
    Nitrogen fixation increases with successional age in boreal forests
    Ecology: 2004 85:3327-3334
  28. Tavares F, Bernardo L, Sellstedt A
    Identification and expression studies of a catalase and a bifunctional catalase-peroxidase in Frankia strain R43
    Plant and Soil: 2003 254:75-81
  29. Leitz G, Lundberg C, Fallman E, Axner O, Sellstedt A
    Laser-based micromanipulation for separation and identification of individual Frankia vesicles
    Fems Microbiology Letters: 2003 224:97-100
  30. Mattsson U, Sellstedt A
    Nickel affects activity more than expression of hydrogenase protein in Frankia
    Curr Microbiol: 2002 44:88-93
  31. DeLuca TH, Zackrisson O, Nilsson M-C, Sellstedt A
    Quantifying nitrogen-fixation in feather moss carpets of boreal forests
    Nature: 2002 419:917-920
  32. Tavares F, Sellstedt A
    DNase-resistant DNA in the extracellular and cell wall-associated fractions of Frankia strains R43 and CcI3
    Curr Microbiol: 2001 42:168-172
  33. Mattsson U, Johansson L, Sandstrom G, Sellstedt A
    Frankia KB5 possesses a hydrogenase immunologically related to membrane-bound
    Curr Microbiol: 2001 42:438-441
  34. Mattsson U, Johansson L, Sandstrom G, Sellstedt A
    Frankia KB5 possesses a hydrogenase immunologically related to membrane-bound [NiFe]-hydrogenases
    Current Microbiology: 2001 42:438-441
  35. Tavares F, Sellstedt A
    A simple, rapid and non-destructive procedure to extract cell wall-associated proteins from Frankia
    J Microbiol Methods: 2000 39:171-178
  36. Mattsson U, Sellstedt A
    Hydrogenase in Frankia KB5: expression of and relation to nitrogenase
    Can J Microbiol: 2000 46:1091-1095
  37. Tavares F, Sellstedt A
    DNase activities of the extracellular, cell wall-associated, and cytoplasmic protein fractions of Frankia strain R43
    Applied and Environmental Microbiology: 1997 63:4597-4599
  38. Sellstedt A
    Specificity and Effectivity in Nodulation by Frankia on Southern-Hemisphere Actinorhiza
    Fems Microbiology Letters: 1995 125:231-236
  39. Sellstedt A, Rosbrook PA, Kang L, Reddell P
    Effect of Carbon Source on Growth, Nitrogenase and Uptake Hydrogenase Activities of Frankia Isolates from Casuarina Sp
    Plant and Soil: 1994 158:63-68
  40. Sellstedt A, Mattsson U
    Hydrogen Metabolism in Casuarina-Frankia - Immunolocalization of Nitrogenase and Hydrogenase
    Soil Biology & Biochemistry: 1994 26:583-592
  41. Sellstedt A, Stahl L, Mattsson U, Jonsson K, Hogberg P
    Can the N-15 Dilution Technique Be Used to Study N-2 Fixation in Tropical Tree Symbioses as Affected by Water-Deficit
    Journal of Experimental Botany: 1993 44:1749-1755
  42. Sellstedt A
    Hydrogen Metabolism in Frankia - Is There a Plant Factor Affecting This Metabolism
    Acta Oecologica-International Journal of Ecology: 1992 13:512-512
  43. Sellstedt A, Wullings B, Nystrom U, Gustafsson P
    Identification of Casuarina-Frankia Strains by Use of Polymerase Chain-Reaction (Pcr) with Arbitrary Primers
    Fems Microbiology Letters: 1992 93:1-5
  44. Sellstedt A, Atkins CA
    Composition of Amino-Compounds Transported in Xylem of Casuarina Sp
    Journal of Experimental Botany: 1991 42:1493-1497
  45. Sellstedt A, Reddell P, Rosbrook P
    The Occurrence of Hemoglobin and Hydrogenase in Nodules of 12 Casuarina-Frankia Symbiotic Associations
    Physiologia Plantarum: 1991 82:458-464
  46. Sellstedt A, Reddell P, Rosbrook PA, Ziehr A
    The Relations of Hemoglobin and Lignin-Like Compounds to Acetylene-Reduction in Symbiotic Casuarina
    Journal of Experimental Botany: 1991 42:1331-1337
  47. Sellstedt A, Winship LJ
    Acetylene, Not Ethylene, Inactivates the Uptake Hydrogenase of Actinorhizal Nodules During Acetylene-Reduction Assays
    Plant Physiology: 1990 94:91-94
  48. Sellstedt A, Lindblad P
    Activities, Occurrence, and Localization of Hydrogenase in Free-Living and Symbiotic Frankia
    Plant Physiology: 1990 92:809-815
  49. Sellstedt A, Smith GD
    Nickel Is Essential for Active Hydrogenase in Free-Living Frankia Isolated from Casuarina
    Fems Microbiology Letters: 1990 70:137-140
  50. Lindblad P, Sellstedt A
    Occurrence and Localization of an Uptake Hydrogenase in the Filamentous Heterocystous Cyanobacterium Nostoc Pcc-73102
    Protoplasma: 1990 159:9-15