Microbial mat diversity from site LN 5
To examine bacterial diversity based on 16S rDNA molecular marker, the V4 hyper-variable region of the 16S rRNA gene was amplified from total DNA using the universal primers 563F and 802R suggested by the Ribosomal Database Project at the Michigan State University (RDP; http://pyro.cme.msu.edu/pyro/help.jsp). The primers contained the Roche 454 sequencing A and B adaptors and a 10 nucleotide “multiple identifier” (MID). PCR amplification was done on a FastStart High Fidelity PCR system (Roche Applied Science, Mannheim, Germany) following the manufacturer's instructions. Five independent PCRs were performed to reduce bias. Two negative controls with no template were also performed. The PCR conditions were 95 °C for 5 min, followed by 30 cycles of 95 °C for 45 s, 57 °C for 45 s and 72 °C for 60 s, and a final elongation step at 72 °C for 4 min. The five reactions were pooled, purified and sequenced on a Genome Sequencer FLX (Roche Applied Science) at the INDEAR genome sequencing facility (Argentina) following the amplicon sequencing protocol provided by the manufacturer.