Project description:Members of the bacterial phylum Spirochaetes are primarily studied for their commensal and pathogenic roles in animal hosts. However, Spirochaetes are also frequently detected in anoxic hydrocarbon-contaminated environments but their ecological role in such ecosystems has so far remained unclear. Here we provide a functional trait to these frequently detected organisms with an example of a sulfate-reducing, naphthalene-degrading enrichment culture consisting of a sulfate-reducing deltaproteobacterium Desulfobacterium naphthalenivorans and a novel spirochete Rectinema cohabitans. Using a combination of genomic, proteomic, and physiological studies we show that R. cohabitans grows by fermentation of organic compounds derived from biomass from dead cells (necromass). It recycles the derived electrons in the form of H2 to the sulfate-reducing D. naphthalenivorans, thereby supporting naphthalene degradation and forming a simple microbial loop. We provide metagenomic evidence that equivalent associations between Spirochaetes and hydrocarbon-degrading microorganisms are of general importance in hydrocarbon- and organohalide-contaminated ecosystems. We propose that environmental Spirochaetes form a critical component of a microbial loop central to nutrient cycling in subsurface environments. This emphasizes the importance of necromass and H2-cycling in highly toxic contaminated subsurface habitats such as hydrocarbon-polluted aquifers.
Project description:A combination of shotgun metaproteomics and 16S rRNA gene pyrosequencing wasused to identify potential functional pathways and key microorganisms involved in long-chain fatty acids (LCFA) anaerobic conversion. Microbial communities degrading saturated- and unsaturated-LCFA were compared. Archaeal communities were mainly composed of Methanosaeta, Methanobacterium and Methanospirillum species, both in stearate (saturated C18:0) and oleate (mono-unsaturated C18:1) incubations. Over 80% of the 16S rRNA gene sequences clustered within the Methanosaeta genus, which is in agreement with the high number of proteins assigned to this group (94%). Archaeal proteins related with methane metabolism were highly expressed. Bacterial communities were rather diverse and the composition dissimilar between incubations with saturated- and unsaturated-LCFA. Stearate-degrading communities were enriched in Deltaproteobacteria (34% of the assigned sequences), while microorganisms clustering within the Synergistia class were more predominant in oleate incubation (25% of the assigned sequences). Bacterial communities were diverse and active, given by the high percentage of proteins related with mechanisms of energy production. Several proteins were assigned to syntrophic bacteria, emphasizing the importance of the interactions between acetogens and methanogens in energy exchange and formation in anaerobic LCFA-rich environments.
Project description:A combination of shotgun metaproteomics and 16S rRNA gene pyrosequencing wasused to identify potential functional pathways and key microorganisms involved in long-chain fatty acids (LCFA) anaerobic conversion. Microbial communities degrading saturated- and unsaturated-LCFA were compared. Archaeal communities were mainly composed of Methanosaeta, Methanobacterium and Methanospirillum species, both in stearate (saturated C18:0) and oleate (mono-unsaturated C18:1) incubations. Over 80% of the 16S rRNA gene sequences clustered within the Methanosaeta genus, which is in agreement with the high number of proteins assigned to this group (94%). Archaeal proteins related with methane metabolism were highly expressed. Bacterial communities were rather diverse and the composition dissimilar between incubations with saturated- and unsaturated-LCFA. Stearate-degrading communities were enriched in Deltaproteobacteria (34% of the assigned sequences), while microorganisms clustering within the Synergistia class were more predominant in oleate incubation (25% of the assigned sequences). Bacterial communities were diverse and active, given by the high percentage of proteins related with mechanisms of energy production. Several proteins were assigned to syntrophic bacteria, emphasizing the importance of the interactions between acetogens and methanogens in energy exchange and formation in anaerobic LCFA-rich environments.
Project description:A combination of shotgun metaproteomics and 16S rRNA gene pyrosequencing wasused to identify potential functional pathways and key microorganisms involved in long-chain fatty acids (LCFA) anaerobic conversion. Microbial communities degrading saturated- and unsaturated-LCFA were compared. Archaeal communities were mainly composed of Methanosaeta, Methanobacterium and Methanospirillum species, both in stearate (saturated C18:0) and oleate (mono-unsaturated C18:1) incubations. Over 80% of the 16S rRNA gene sequences clustered within the Methanosaeta genus, which is in agreement with the high number of proteins assigned to this group (94%). Archaeal proteins related with methane metabolism were highly expressed. Bacterial communities were rather diverse and the composition dissimilar between incubations with saturated- and unsaturated-LCFA. Stearate-degrading communities were enriched in Deltaproteobacteria (34% of the assigned sequences), while microorganisms clustering within the Synergistia class were more predominant in oleate incubation (25% of the assigned sequences). Bacterial communities were diverse and active, given by the high percentage of proteins related with mechanisms of energy production. Several proteins were assigned to syntrophic bacteria, emphasizing the importance of the interactions between acetogens and methanogens in energy exchange and formation in anaerobic LCFA-rich environments.
Project description:A combination of shotgun metaproteomics and 16S rRNA gene pyrosequencing wasused to identify potential functional pathways and key microorganisms involved in long-chain fatty acids (LCFA) anaerobic conversion. Microbial communities degrading saturated- and unsaturated-LCFA were compared. Archaeal communities were mainly composed of Methanosaeta, Methanobacterium and Methanospirillum species, both in stearate (saturated C18:0) and oleate (mono-unsaturated C18:1) incubations. Over 80% of the 16S rRNA gene sequences clustered within the Methanosaeta genus, which is in agreement with the high number of proteins assigned to this group (94%). Archaeal proteins related with methane metabolism were highly expressed. Bacterial communities were rather diverse and the composition dissimilar between incubations with saturated- and unsaturated-LCFA. Stearate-degrading communities were enriched in Deltaproteobacteria (34% of the assigned sequences), while microorganisms clustering within the Synergistia class were more predominant in oleate incubation (25% of the assigned sequences). Bacterial communities were diverse and active, given by the high percentage of proteins related with mechanisms of energy production. Several proteins were assigned to syntrophic bacteria, emphasizing the importance of the interactions between acetogens and methanogens in energy exchange and formation in anaerobic LCFA-rich environments.