Archaea Diversity in Brazilian Aquatic Ecosystems pp. 95-120
Authors: (Flávia Talarico Saia, Ana Carolina Araujo, Cristina Rossi Nakayama, Diego Assis das Graças, Juliana Perez Chaparro, Fernando Andreote, Rodrigo Taketani, Fernanda Piza, Artur Silva, Vivian Helena Pellizari, Itamar Soares, Gilson Manfio and Rosana Filomena Vazoller, Laboratory of Biological Process, Engineering School of São Carlos, University of São Paulo. Av. Trabalhador São-carlense, 400, 13566-590, São Carlos, SP, Brazil, and others)
Abstract: Comparative sequence analysis of 16S RNA molecules carried out by Carl Woese in the 1970s revealed that life on Earth can be divided into three primary lineages (referred to as domains): Eukarya, Bacteria and Archaea. Presently, most known archaeal representatives are included into two kingdoms: Crenarchaeota and Euryarchaeota, with remarkable diversity of organisms. Archaea can be found in some of the most extreme environments on the planet, but are not restricted to them. Although the important role that Archaea play in biogeochemical cycles, such as carbon, sulfur and nitrogen cycles, physiology and ecological significance of archaeal populations are still poorly known.
This lack of knowledge is, in large part, due to the limitations of cultivation procedures. In addition, information about the archaeal community in tropical ecosystems is still scarce. In this chapter we present a survey of the archaeal community present in aquatic ecosystems of Brazil: Madeira River and Tucuruí Power Plant Reservoir in Amazon; Santos and São Vicente Estuary and mangroves in the Southeast coast. The study of archaeal groups in freshwater and saline tropical aquatic ecosystems in Brazil revealed highly diverse communities and suggested the presence of new archaeal groups. In Amazonian environments, Crenarchaeota representatives such as Marine Group I, 1.1.band Thermoplasmata were frequent, suggesting a possible role of Archaea in nitrogen and carbon metabolism. Methanogenic groups were also detected in sediment and water where anaerobic conditions prevailed from both regions studied. In Santos and São Vicente Estuarine System, higher abundance of methanogenic Archaea was found in a highly impacted site when compared to a less contaminated area. In Mangrove sediments, the detection of MCG, MBG-B and MBG-D as an important component of the microbial community indicates the possible role of these groups in carbon cycle. This work emerges as a valuable contribution to the understanding of the biogeography and diversity of Archaea Domain in these rich ecosystems, besides providing hints as to help characterizing the role and dynamics of archaeal communities in major processes such methane production in tropical environments, subjected or not to the influence of human activities.