Abstract
Methanogenic archaeans are organisms of considerable ecological and biotechnological interest that produce methane through a restricted metabolic pathway, which culminates in the reaction catalyzed by the Methyl-coenzyme M reductase (Mcr) enzyme, and results in the release of methane. Using a metagenomic approach, the gene of the α subunit of mcr (mcrα) was isolated from sediment sample from an anoxic zone, rich in decomposing organic material, obtained from the Tucuruí hydroelectric dam reservoir in eastern Brazilian Amazonia. The partial nucleotide sequences obtained were 83 to 95% similar to those available in databases, indicating a low diversity of archaeans in the reservoir. Two orders were identified - the Methanomicrobiales, and a unique Operational Taxonomic Unit (OTU) forming a clade with the Methanosarcinales according to low bootstrap values. Homology modeling was used to determine the three-dimensional (3D) structures, for this the partial nucleotide sequence of the mcrα were isolated and translated on their partial amino acid sequences. The 3D structures of the archaean Mcrα observed in the present study varied little, and presented approximately 70% identity in comparison with the Mcrα of Methanopyrus klanderi. The results demonstrated that the community of methanogenic archaeans of the anoxic C1 region of the Tucurui reservoir is relatively homogeneous.
Highlights
The organisms of the Domain Archaea (Woese et al, 1990) constitute a considerable proportion of the prokaryotes found in both aquatic and terrestrial ecosystems, where they are active in the carbon biogeochemical cycle
For the second curve (Figure 2B), we added, to the original 28 sequences, the sequences obtained using the primers according to Luton et al (2002) resulting in a total of 113 nucleotide sequences, by which Dotur identified 58 unique Operational Taxonomic Unit (OTU)
The nucleotide (Figure 3A) and amino acid (Figure 3B) trees generated by the MEGA program from the 18 unique OTUs are both characterized by three distinct clades, the nucleotide cladogram returned higher bootstrap values
Summary
The organisms of the Domain Archaea (Woese et al, 1990) constitute a considerable proportion of the prokaryotes found in both aquatic and terrestrial ecosystems, where they are active in the carbon biogeochemical cycle. The methanogenic archaea are of special interest because of their capacity to reduce CO2 and other compounds in the presence of H2 (Conrad, 1999), under anoxic conditions, to produce methane through a process known as methanogenesis (Zehnder and Brock, 1979). Archaean communities are distributed worldwide, and are known for their considerable heterogeneity (Schleper et al, 2005). Studies of the diversity of archaean communities have been conducted in a variety of environments, from hot (Martinez et al, 2006) and hypersaline (Oren, 2002) lakes, anoxic zones (Lehours et al, 2007) and marine sediments (Teske and Sørensen, 2008) to the digestive systems of ruminants and humans (Lange and Ahring, 2001)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
