Project

Discipline

spore-forming bacteria; metagenomics; metabolic reconstruction; extreme environments

Lead
Lay summary
Microbial spores are believed to have evolved as a mechanism for spatial and temporal escape from unfavorable environmental conditions. Research in spore-forming bacteria is focused so far in pathogens (e.g., anthrax) or food-biotechnology (e.g., probiotics), while the environmental role and metabolic diversity of spore-forming bacteria have remain relatively unexplored. Recently, spore-forming bacteria have been detected as dominant members of the microbial communities in metal-contaminated sites, suggesting that these microorganisms might play an important role in metal decontamination. Additionally, spore-forming bacteria (Desulfotomaculum spp., Carboxydothermus hydrogenoformans Z-2901, and Candidatus Desulforudis audaxviator) have been detected in microbial communities inhabiting extreme environments such as deep mines or geothermal sites. This suggests that spore-forming bacteria are not only more diverse than previously thought, but also that they should display a wide metabolic repertory that allow them to dominate microbial communities in environments with extreme conditions. Despite the contribution of spore-forming bacteria to the microbial communities in contaminated or extreme environments, they have been largely overlooked by traditional and molecular techniques used in microbial ecology. Although new molecular approaches have started to reveal the extent of the microbial diversity in different environments, this is not the case for spore-forming bacteria because DNA-based techniques do not capture spore-forming bacteria if they are found in the spore form. The aim of this proposal is to characterize the metabolic capabilities of spore-forming microorganisms in environments in which the production of spores could result in an advantage for survival (contaminated subsurface or geothermal sites). We propose to start by the isolation of spores, followed by the analysis of their metabolic capabilities through environmental genomics. Additionally, we propose to isolate and cultivate spore-forming bacteria. In both cases we expect to discover new metabolic properties that can contribute to explain the role of spore-formers in environmental samples. With this proposal we expect to contribute basic knowledge regarding the metabolic diversity of spore-forming bacteria. We also expect that by the characterization of a hitherto neglected group of microorganisms we will open a new an exciting that can constitute the basis for future research lines in microbiology. The information obtained can also help us to better understand the role of spore-formers in environmental samples.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

Microbial spores, highly resistant resting states able to tolerate harsh conditions, are believed to have evolved as a mechanism for spatial and temporal escape from unfavorable environmental conditions. However, research in spore-forming bacteria has been mainly focused in the associated diseases (e.g., anthrax), and more recently in food-biotechnology (e.g., probiotics), while the environmental role and metabolic diversity of spore-forming bacteria have remain relatively unexplored. Recently, spore-forming bacteria have been detected as dominant members of the microbial communities in metal-contaminated sites, suggesting that these microorganisms might play an important role in metal decontamination. As an example of this we have characterized some of the metabolic properties of Desulfotomaculum reducens MI-1, an environmentally-relevant spore-forming bacterium. We have found that it is able to reduce a variety of metals and/or anthropogenic contaminants including Fe(III), Cr(VI), Se(IV), As(V), Te(IV), and U(VI). There is also emerging evidence in the literature of metal reduction by other groups of spore-forming microorganisms (e.g. Clostridium spp., Desulfosporosinus spp., and Alkaliphilus metalliredigens), supporting the idea that spore-formers contribute to the metabolism of heavy metals. Additionally, spore-forming bacteria (Desulfotomaculum spp., Carboxydothermus hydrogenoformans Z-2901, and Candidatus Desulforudis audaxviator) have been detected in microbial communities inhabiting extreme environments such as deep mines or geothermal sites. This suggests that spore-forming bacteria are not only more diverse than previously thought, but also that they should display a wide metabolic repertory that allow them to dominate microbial communities in environments with extreme conditions (e.g. high temperature, lack of electron donors, varying conditions of oxygen and moisture, high pollution). Despite the contribution of spore-forming bacteria to the microbial communities in contaminated or extreme environments, they have been largely overlooked by traditional and molecular techniques used in microbial ecology. Although new molecular approaches have started to reveal the extent of the microbial diversity in different environments, this is not the case for spore-forming bacteria because DNA-based techniques do not capture spore-forming bacteria if they are found in the spore form. The aim of this proposal is to characterize the metabolic capabilities of spore-forming microorganisms in environments in which the production of spores could result in an advantage for survival (contaminated subsurface or geothermal sites). We propose to start by the isolation of spores, followed by the analysis of their metabolic capabilities through environmental genomics. Additionally, we propose to isolate and cultivate spore-forming bacteria. In both cases we expect to discover new metabolic properties that can contribute to explain the role of spore-formers in environmental samples.