title: Diversity and identification of methanogenic archaea and sulphate-reducing bacteria in sediments from a pristine tropical mangrove.
abstract: Mangrove sediments are anaerobic ecosystems rich in organic matter. This environment is optimal for anaerobic microorganisms, such as sulphate-reducing bacteria and methanogenic archaea, which are responsible for nutrient cycling. In this study, the diversity of these two functional guilds was evaluated in a pristine mangrove forest using denaturing gradient gel electrophoresis (DGGE) and clone library sequencing in a 50 cm vertical profile sampled every 5.0 cm. DGGE profiles indicated that both groups presented higher richness in shallow samples (0-30 cm) with a steep decrease in richness beyond that depth. According to redundancy analysis, this alteration significantly correlated with a decrease in the amount of organic matter. Clone library sequencing indicated that depth had a strong effect on the selection of dissimilatory sulphate reductase (dsrB) operational taxonomic units (OTUs), as indicated by the small number of shared OTUs found in shallow (0.0 cm) and deep (40.0 cm) libraries. On the other hand, methyl coenzyme-M reductase (mcrA) libraries indicated that most of the OTUs found in the shallow library were present in the deep library. These results show that these two guilds co-exist in these mangrove sediments and indicate important roles for these organisms in nutrient cycling within this ecosystem.
authors.affiliation: Molecular and Cellular Biology, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, 303 Centenário Av., Piracicaba, SP, Brazil. rgtaketani@yahoo.com.br
authors.forename: Rodrigo Gouvêa
authors.initials: RG
authors.lastname: Taketani
authors.forename: Caio Augusto
authors.initials: CA
authors.lastname: Yoshiura
authors.forename: Armando Cavalcante Franco
authors.initials: AC
authors.lastname: Dias
authors.forename: Fernando Dini
authors.initials: FD
authors.lastname: Andreote
authors.forename: Siu Mui
authors.initials: SM
authors.lastname: Tsai
mesh_terms: D001105:Archaea / Q000145:classification* / Q000378:metabolism; D019843:Archaeal Proteins / Q000235:genetics; D001419:Bacteria / Q000145:classification* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D044822:Biodiversity; D004591:Electrophoresis, Polyacrylamide Gel; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation; D010084:Oxidation-Reduction; D043982:Rhizophoraceae / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D013431:Sulfates; D008697:Methane