|70-2||C14-AHL signalling molecules enhances biofilm formation on metal sulfides by the extremophilic bacterium Acidithiobacillus ferrooxidans
|Autores:||Alex Gonzalez (UCH - Universidad de Chile - Facultad de Ciencias) ; Sören Bellenberg (UDE - Biofilm Centre Aquatische Biotechnologie, Universitätstr 5) ; Sigde Mamani (UCH - Universidad de Chile - Facultad de Ciencias / CNRS - Institut de Microbiologie de la Méditerranée / AMU - Université d'Aix-Marseille, Facultés des Sciences) ; Alex Echeverría (UCN - Biotechnology Center, Universidad Católica del Norte) ; Laurent Soulère (INSA-CNRS - ICBMS, Chimie Organique et Bioorganique, INSA Lyon) ; Cecilia Demergasso (UCN - Biotechnology Center, Universidad Católica del Norte) ; Yves Queneau (INSA-CNRS - ICBMS, Chimie Organique et Bioorganique, INSA Lyon) ; Mario Vera (UDE - Biofilm Centre Aquatische Biotechnologie, Universitätstr 5) ; Nicolas Guiliani (UCH - Universidad de Chile - Facultad de Ciencias) |
Research on bioleaching must consider as goals the enhancement of bioleaching rates to improve the metallurgical performance in industrial processes activity and their inhibition in order to mitigate AMD/ARD. Comprehension of the physiology and the adaptive molecular mechanisms of bioleaching microorganisms is thus an extremely important issue.
Bacterial attachment and biofilm formation on minerals increases leaching activities due to the formation of a reaction space between the sulfide ore surface and the cell. Biofilm development is a complex process that is regulated by cell-to-cell communication mechanisms named Quorum Sensing (QS) in many Gram-negative bacteria.
Acidithiobacillus ferrooxidans is an acidophilic, chemolithoautrophic Gram-negative bacterium that has an important role in metal leaching and AMD/ARD production. It belongs to the consortia of microorganisms related with bioleaching processes, and possesses a functional type AI-1 QS system that involves acyl-homoserine lactone (AHLs) as autoinducer molecules.
The At. ferrooxidans QS system (afeI/afeR) has been proposed that could be involved in the production of EPS and consequently in the regulation of biofilm formation. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium At. ferrooxidans on sulfur and pyrite surfaces by using QS signalling molecules.
Our results revealed that AHL-signalling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of At. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous At. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances (EPS).
These results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.
Acknowledgements. This work was supported by grants FONDECYT 1080441 and 1120295. Alex González was supported by scholarships from CONICYT. Sören Bellenberg and Mario Vera acknowledge the financial support of the program of promotion of Young Scientists from University of Duisburg-Essen.
Palavras-chave: Biomining, Biofilm, Acidithiobacillus ferrooxidans, Quorum sensing, Atomic force microscopy