Microbial Diversity of an Anoxic Zone of a Hydroelectric Power Station Reservoir in Brazilian Amazonia

Abstract

Microbial diversity was evaluated in an anoxic zone of Tucuruí Hydroelectric Power Station reservoir in Brazilian Amazonia using a culture-independent approach by amplifying and sequencing fragments of the 16S rRNA gene using metagenomic DNA as a template. Samples obtained from the photic, aphotic (40 m) and sediment (60 m) layers were used to construct six 16S rDNA libraries containing a total of 1,152 clones. The sediment, aphotic and photic layers presented 64, 33 and 35 unique archaeal operational taxonomic units (OTUs). The estimated richness of these layers was evaluated to be 153, 106 and 79 archaeal OTUs, respectively, using the abundance-based coverage estimator (ACE) and 114, 83 and 77 OTUs using the Chao1 estimator. For bacterial sequences, 114, 69 and 57 OTUs were found in the sediment, aphotic and photic layers, which presented estimated richnesses of 1,414, 522 and 197 OTUs (ACE) and 1,059, 1,014 and 148 OTUs (Chao1), respectively. Phylogenetic analyses of the sequences obtained revealed a high richness of microorganisms which participate in the carbon cycle, namely, methanogenic archaea and methanotrophic proteobacteria. Most sequences obtained belong to non-culturable prokaryotes. The present study offers the first glimpse of the huge microbial diversity of an anoxic area of a man-made lacustrine environment in the tropics.

Bacterial Diversity in an Amazonian Mangrove Ecosystem

“…This result was also verified by Shannon and Chao diversity indice and the rarefaction curves. Similar results have been observed in a number of previous studies (Kemp & Aller 2004;Lozupone & Knight, 2007;Caporaso et al, 2011;Graças et al, 2011).…”

Microbial and Chemical Characterization of Underwater Fresh Water Springs in the Dead Sea

“…8C). It has been shown before that this deep sea group of the Halobacteria can thrive in less saline environments [63], [64]. The Thermoplasmata -associated sequences from the springs cluster with samples from deep hydrothermal vents as well.…”

Archaea in Natural and Impacted Brazilian Environments

“…While most of the research performed in marine environments has been done in the southeast and northeast regions, the articles describing freshwater Archaea communities were made mainly in the Amazon region (located in the north region of Brazil) and in states located in the south region, such as Paraná and Rio Grande do Sul [41–46]. One exception is one study that described the freshwater archaeal community found in Ilha Grande, Rio de Janeiro, where the phylogenetic tree revealed that the DNA sequences obtained were affiliated to the Thaumarchaeota clade, especially to N. maritimus [25].…”

“…Globally the authors described that their samples presented 30% of Methanomicrobia and 40% of Thermoprotei. The photic zone revealed a higher proportion of euryarchaeotes and crenarchaeotes, while the aphotic zone was rich in methanogenic and halophilic archaea [41]. …”