PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
ZeoBioFilms: Exploring mineral-microbe interactions on synthetic zeolites
Autor/es:
CASTRO, M.; SMITH, R.; CUBILLAS P.; ANDERSON, M.; FARIAS, M.E.; ALBARRACÍN V.H.
Lugar:
Moscú
Reunión:
Conferencia; 17th International Zeolite Conference (17th IZC); 2013
Resumen:
Introduction The interaction zeolites-bacteria to form biofilms has been reported in soils (zeolite bio-fertilizer) as enhancer of plant growth. The active mineralization is caused by a large increase in the population of chemolithotrophic nitrifying bacteria, supported initially by NH4+ ions diffusing from the ammoniated zeolite in the bio-fertilizer. The addition of untreated zeolite tuff substantially increases the plant growth since enhances the microbial activity. That proves i) that zeolites are suitable materials to support life and ii) that the extracellular polymeric substrates (EPS) segregated by bacteria allow their attachment to zeolite surface. Up to date there is not enough studies on the mechanisms of silification or dissolution of zeolites based on microbial activity and how these EPS could modify the zeolite?s surface. Our research aims to unravel at a molecular scale these two open questions. This work presents a preliminary approach to develop novel biofilms of extremophilic bacteria. on well characterized surfaces of zeolitic materials such as zeolite ZSM-5 and zeotype STA-7. Experimental Two extremophilic bacterial strains isolated from High-Altitude Andean Lakes (HAAL) in Argentinean Puna: Acinetobacter sp. Ver3 (a planktonic strain from Lake Verde, 4,400 m) and Exiguobacterium sp. S17 (isolated from a modern stromatolite at Lake Socompa, 3,570 m) were used for exploring biofilm formation on well-defined crystals of STA-7 and ZSM-5 zeolites. Cells were grown in synthetic liquid media containing zeolites for 4 days (30 °C, 200 rpm), then cells were centrifuged and left to starve on the zeolites surface at 30 °C. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used among other techniques to investigate the modifications on the surfaces of the zeolitic materials when cells were still attached and after biofilm removal. Results and discussion The surface of the zeolitic materials was characterized by AFM and specific conditions for the biofilm formation are at the moment under optimization. Nevertheless, extremophiles obtained from the plankton or from the stromatolite have been successfully growth on the surface of the materials as observed by SEM. Outlook Preliminary results prove for the first time the plausible formation of biofilms of extremophilic bacteria (resistant to UV and arsenic) isolated from HAAL on synthetic zeolites. Research on microbial-mineral interactions can lead to important results not only for their direct applications in the modification of zeolites to generates mesoporosity and the assembly of biofilms but also to advance on knowledge in the area of evolution of life and astrobiology. Acknowledgements Funding by the Max-Planck-Gesellschaft (MPG), the European Commission (International Incoming Fellowship Marie Curie ?EXTREMOPHIL?) and EPSRC is acknowledged. Ulla Wilczok is acknowledged for fruitful discussion for the synthesis of our ZSM-5 samples and Silvia Palm for preliminary SEM data collection.