Project description:Propionate accumulation is an important bottleneck for anaerobic degradation of organic matter. We hypothesized that propionate conversion by a novel coculture of Syntrophobacter fumaroxidans and Geobacter sulfurreducens can be an alternative strategy for propionate oxidation coupled to Fe(III) reduction. In this study, we successfully cocultured S. fumaroxidans and G. sulfurreducens on propionate and Fe(III). Proteomic analyses of this coculture provided insights into the underlying mechanisms of propionate metabolism pathway and interspecies electron transfer mechanism. Our study can be further useful in understanding syntrophic propionate degradation in bioelectrochemical and anaerobic digestion systems.
Project description:Anode-associated multi-species exoelectrogenic biofilms are essential to the function of bioelectrochemical systems (BESs). The investigation of electrode-associated biofilms is critical to advance understanding of the function of individual members within communities that thrive using an electrode as the terminal electron acceptor. This study focusses on the analysis of a model biofilm community consisting of Shewanella oneidensis, Geobacter sulfurreducens and Geobacter metallireducens. The conducted experiments revealed that the organisms can build a stable biofilm on an electrode surface that is rather resilient to changes in the redox potential of the anode surface. The community operated at maximum electron transfer rates with electrode potentials of 0.04 V versus normal hydrogen electrode. Current densities decreased gradually with lower potentials and reached half-maximal values at -0.08 V. A positive interaction of the individual strains could be observed in our experiments. At least S. oneidensis and G. sulfurreducens show an upregulation of their central metabolism as a response to cultivation under mixed-species conditions. Interestingly, G. sulfurreducens was detected in the planktonic phase of the bioelectrochemical reactors only in mixed-culture experiments but not when it was grown in the absence of the other two organisms. It is possible that G. sulfurreducens cells used flavins which were released by S. oneidensis cells as electron shuttles. This would allow the organism to broaden its environmental niche. To the best of our knowledge, this is the first study describing the dynamics of biofilm formation of a model exoelectrogenic community, the resilience of the biofilm, and the molecular responses towards mixed-species conditions.
2017-01-18 | GSE79750 | GEO
Project description:Bioaugmentation performance of aerobic denitrifiers
