First Archaeal rDNA sequences from coastal waters of Argentina: unexpected PCR characterization by using eukaryotic primers

F. COVACEVICH; R.I. SILVA; A.C. CUMINO; G.F. CALÓ; R.M. NEGRI; G.L. SALERNO

CIENCIAS MARINAS

INST INVESTIGACIONES OCEANOLOGICAS, U A B C, APARTADO POSTAL 423

Lugar: Ciudad de México; Año: 2011

0185-3880

Many members of Archaea, a group of prokaryotes recognized three decades ago, colonize extreme environments. However, new research is showing that Achaeans are also quite abundant in the plankton of the open sea, where are fundamental components that play a key role in the biogeochemical cycles. Although the widespread distribution of Archaea the marine environment is well documented there are no reports on the detection of Archaea in the Southwest Atlantic Ocean. During the search of picophytoplankton sequences using eukaryotic universal primers, we retrieved archaeal rDNA sequences from surface samples collected during Spring at the fixed EPEA Station (38º28’S-57º41’W, Argentine Sea). From environmental DNA and using PCR methodology, two DNA fragments of about 1,700 and 1,450 bp were visualized after electrophoresis in agarose gels, which were separately purified, cloned and sequenced. BLAST analysis showed that sequences of the highest size corresponded to eukaryotic organisms and, unexpectedly, those of about 1,460 bp corresponded to Archaeal organisms. Phylogenetic analysis showed that Archaeal sequences belong to Euryarchaeota of the Marine Group II, which is characterized as a methanogenic lineage. This is the first report on the presence of Euryarchaeota-Group II sequences in environmental water samples of the Argentine Sea. The fact that Archaea sequences were amplified with primers non specific for this group may suggest an unexpected abundance of these organisms in the early spring in the Argentine Sea.