Carbon capture and utilization has been proposed as one strategy to combat global warming. Microbial electrolysis cells (MECs) combine the biological conversion of carbon dioxide (CO2) with the formation of valuable products such as methane. This study was motivated by the surprising gap in current knowledge about the utilization of real exhaust gas as a CO2 source for methane production in a fully biocatalyzed MEC. Therefore, two steel mill off-gases differing in composition were tested in a two-chamber MEC, consisting of an organic substrate-oxidizing bioanode and a methane-producing biocathode, by applying a constant anode potential. The methane production rate in the MEC decreased immediately when steel mill off-gas was tested, which likely inhibited anaerobic methanogens in the presence of oxygen. However, methanogenesis was still ongoing even though at lower methane production rates than with pure CO2. Subsequently, pure CO2 was studied for methanation, and the cathodic biofilm successfully recovered from inhibition reaching a methane production rate of 10.8 L m-2d-1. Metagenomic analysis revealed Geobacter as the dominant genus forming the anodic organic substrate-oxidizing biofilms, whereas Methanobacterium was most abundant at the cathodic methane-producing biofilms.

• Klíčová slova
• bioelectrodes, electromethanogenesis, exhaust gas, metagenomic analysis, microbial electrolysis cell,
• Publikační typ
• časopisecké články MeSH

The variation in the diversity of methanogens in sediment depths from Sitka stream was studied by constructing a 16S rRNA gene library using methanogen-specific primers and a denaturing gradient gel electrophoresis (DGGE)-based approach. A total of nine different phylotypes from the 16S rRNA library were obtained, and all of them were clustered within the order Methanosarcinales. These nine phylotypes likely represent nine new species and at least 5-6 new genera. Similarly, DGGE analysis revealed an increase in the diversity of methanogens with an increase in sediment depth. These results suggest that Methanosarcinales phylotypes might be the dominant methanogens in the sediment from Sitka stream, and the diversity of methanogens increases as the depth increases. Results of the present study will help in making effective strategies to monitor the dominant methanogen phylotypes and methane emissions in the environment.

• MeSH
• denaturační gradientová gelová elektroforéza MeSH
• DNA archebakterií chemie   genetika   MeSH
• fylogeneze MeSH
• geologické sedimenty mikrobiologie   MeSH
• Methanosarcinales izolace a purifikace   MeSH
• molekulární sekvence - údaje MeSH
• řeky MeSH
• ribozomální DNA chemie   genetika   MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• společenstvo * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• DNA archebakterií MeSH
• ribozomální DNA MeSH
• RNA ribozomální 16S MeSH

Methane production by intestinal methanogenic Archaea and their community structure were compared among phylogenetic lineages of millipedes. Tropical and temperate millipedes of 35 species and 17 families were investigated. Species that emitted methane were mostly in the juliform orders Julida, Spirobolida, and Spirostreptida. The irregular phylogenetic distribution of methane production correlated with the presence of the methanogen-specific mcrA gene. The study brings the first detailed survey of methanogens' diversity in the digestive tract of millipedes. Sequences related to Methanosarcinales, Methanobacteriales, Methanomicrobiales and some unclassified Archaea were detected using molecular profiling (DGGE). The differences in substrate preferences of the main lineages of methanogenic Archaea found in different millipede orders indicate that the composition of methanogen communities may reflect the differences in available substrates for methanogenesis or the presence of symbiotic protozoa in the digestive tract. We conclude that differences in methane production in the millipede gut reflect differences in the activity and proliferation of intestinal methanogens rather than an absolute inability of some millipede taxa to host methanogens. This inference was supported by the general presence of methanogenic activity in millipede faecal pellets and the presence of the 16S rRNA gene of methanogens in all tested taxa in the two main groups of millipedes, the Helminthophora and the Pentazonia.

• MeSH
• biodiverzita * MeSH
• členovci mikrobiologie   MeSH
• denaturační gradientová gelová elektroforéza MeSH
• Euryarchaeota genetika   metabolismus   fyziologie   MeSH
• feces chemie   MeSH
• fylogeneze MeSH
• gastrointestinální trakt mikrobiologie   MeSH
• methan biosyntéza   metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Rumunsko MeSH
• Slovenská republika MeSH
• Názvy látek
• methan MeSH
• RNA ribozomální 16S MeSH

Methanogenic archaea produce methane as a metabolic product under anoxic conditions and they play a crucial role in the global methane cycle. In this study molecular diversity of methanogenic archaea in the hyporheic sediment of the lowland stream Sitka (Olomouc, Czech Republic) was analyzed by PCR amplification, cloning and sequencing analysis of the methyl coenzyme M reductase alpha subunit (mcrA) gene. Sequencing analysis of 60 clones revealed 24 different mcrA phylotypes from hyporheic sedimentary layers to a depth of 50 cm. Phylotypes were affiliated with Methanomicrobiales, Methanosarcinales and Methanobacteriales orders. Only one phylotype remains unclassified. The majority of the phylotypes showed higher affiliation with uncultured methanogens than with known methanogenic species. The presence of relatively rich assemblage of methanogenic archaea confirmed that methanogens may be an important component of hyporheic microbial communities and may affect CH4 cycling in rivers.

• MeSH
• Archaea genetika   MeSH
• archeální geny MeSH
• fylogeneze MeSH
• genová knihovna MeSH
• geologické sedimenty mikrobiologie   MeSH
• methan metabolismus   MeSH
• mikrobiologie životního prostředí MeSH
• molekulární sekvence - údaje MeSH
• řeky mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• methan MeSH