IMIS

Duplicate samples were collected at depths of 6 m (bacterial and primary production maximum) and 9 m (chemocline; chlorophyll-a maximum) in lake Fryxell (2 November 2007 and 25 March 2008) and 13 m (chemocline; bacterial production, chlorophyll-a, primary production maximum) and 18 m (hypersaline, bottom of trophogenic zone) in lake Bonney (west Lobe; 30 November 2007 and 12 March 2008). Samples for DNA extraction were filtered onto 0.2-μM Sterivex filters (Millipore, Billerica, MA, USA) and stored with 2.0 ml of Puregene lysis buffer at −20 °C until further processing.
Study Extent: Sampling occurred during the Austral summer and autumn in lake Fryxell and lake Bonney, Antarctica
Method step description:

1. DNA extraction protocols can be found at http://amarallab.mbl.edu.
2. The V6 hypervariable regions of Archaa and bacteria were amplified, while for Eukaryota, amplification of the V9 hypervariable region followed established protocols (Amaral-Zettler et al., 2009). We multiplex-sequenced the resulting amplicons using bar-coded primers (Huber et al., 2007; Amaral-Zettler et al., 2009) on a 454 Genome Sequencer FLX (Roche, Switzerland) using the manufacturer’s recommended protocol.