Dr. Johannes Raff

Head Biogeochemistry
Phone: +49 351 260 2951

Department of Biogeochemistry


In the environment physical, chemical and biological processes influence the migration behavior of long-lived radionuclides. In the biosphere mainly prokaryotic and eukaryotic microorganisms are involved in element cycles and the mobilization or immobilization of many radioactive and non-radioactive elements. Furthermore, their physiology and biochemistry are optimized to allow them to live and survive in almost all environments existing on earth even over long periods of time. Besides that, the interaction of microbes with radionuclides and with higher organisms determine the fate of the radionuclides in nature and in the end their potential threat to human health. The aim of the research in the Department of Biogeochemistry is thus to identify dominating processes in the ecosphere including the food chain, to understand the biochemistry of the processes on a molecular level and to estimate their relevance for the radionuclides migration not only in nature but also in an engineered subsurface e.g. a deep-geological repository for radioactive waste. Beside the fundamental research it is also intended to generate thermodynamic data to improve the safety assessment modelling.

Current research topics

  • Determination of the microbial diversity in water and soil environments contaminated with heavy metals and radionuclides as well as in different host rocks for radioactive waste disposals:
    • culture-independent approaches:
      Extraction of DNA, PCR, Sanger sequencing, Next Generation Sequencing
    • culture-dependent approaches:
      Enrichment, Isolation, characterization and cultivation of microbial isolates recovered from above environments, e.g. bacteria, archaea und fungi
  • Microbe-radionuclide-interactions with reference strains and isolates:
    • Biosorption, bioaccumulation and biotransformation of radionuclides by bacteria, archaea, algae and fungi
    • Tolerance of microbes to different radionuclides
    • Analysis of the genetic determinants responsible for the microbe-radionuclide interactions
    • Investigation of bacterial S-layer proteins isolated from bacteria living in uranium mining waste piles: metal-structure relationship and metal clustering
    • Studies on microbe-uranium interaction in flooding waters of former uranium mines for bioremediation and upscaling of the processes for the construction of a pilot plant.
  • Interaction of eukaryotic cells with radionuclides and lanthanides in particular with plants, fungi, sponges and algae
  • Investigation of the interaction of selected bioligands and model compounds with f-elements:
    • Complex formation of actinides with flavonoides and badiones
    • Investigation of the interaction of f-elements with calmodulin and phosvitin
  • Characterization of microbial processes affecting the conditions in deep geological repository for radioactive waste (e.g. transformation of bentonite as barrier material)
  • Calculation and determination of the metal speciation relevant to the environment
  • Verification and validation of transport models
  • Characterization of particles in the environment relevant to the transport of radionuclides
  • Investigation of the transport processes of radionuclides by particles (including microbes) in natural water

Experimental methods

  • Spectroscopy: LIFS (TRLFS, LIPAS); continuous wave fluorescence spectroscopy, UV-vis-NIR, XAS, Raman
  • Molecular biology (DNA extraction, PCR, Sanger sequencing, Next Generation Sequencing, heterologous expression of proteins)
  • Aerobic and anaerobic lab-scale cultivation of microorganisms in bioreactors (1-50 L)
  • Cell disruption in small and large volumes (mixer mill, ultra-sonic disruption, bead ruptor, high pressure homogenizer)
  • Microscopy: CLSM, REM, TEM, AFM
  • Chromatography: HPLC, FPLC
  • Protein biochemistry (isolation and characterization)


  • MIND, EU project, grant agreement No 661880, duration 01.06.2015 – 31.05.2019
  • BioVeStRa, BMBF support code 02S9276A, duration 01.06.2016-31.05.2019
  • CONCERT: European Joint Programme for the Integration of Radiation Protection Research; EC-Project grant agreement No 662287, duration 2015 -2020
  • TransAqua, BMBF support code 02NUK030F, duration 01.06.2013-30.11.2017
  • UMB project, BMWI support code 02E11344B, duration 01.04.2015-31.12.2017
  • BioNEWS, BMBF support code 03WKCL03F, duration 01.01.2015-31.12.2017
  • TRANS-LARA, BMBF support code 02NUK051B, duration 01.09.2017-31.08.2020


For more information, move the cursor over the images or click the persons image!

FWOB Katrin Flemming Dr. Susanne Sachs Dr. Andrea Cherkouk Jenny Jessat Stephan Hilpmann Dr. Evelyn Krawczyk-Bärsch Dr. Alix Günther Dr. Nicole Matschiavelli Dr. Poulami Mandal Dr. Henry Moll Sindy Kluge Björn Drobot Magdalena Dressler Dr. Warren John Vladyslav Sushko Sylvia Heller Dr. Johannes Raff


NameBld./Office+49 351 260Email
Raff Dr., Johannes801/P3142951


NameBld./Office+49 351 260Email
Cherkouk Dr., Andrea801/P3562989
Dressler, Magdalena801/P3482386
Drobot Dr., Björn801/P3182759
Flemming, Katrin801/P3092958
Hilpmann, Stephan801/P3062860
Jessat, Jenny801/P2052438
John Dr., Warren801/P3063241
Krawczyk-Bärsch Dr., Evelyn801/P2522076
Mandal Dr., Poulami801/P3063241
Matschiavelli Dr., Nicole801/P3063241
Moll Dr., Henry801/P2562433
Sachs Dr., Susanne801/P2082436
Seibt, Jana801/P2193194


Dr. Johannes Raff

Head Biogeochemistry
Phone: +49 351 260 2951