DNA sequence data collected during the SIPEX II voyage of the Aurora Australis, 2012

Cells in sea-ice brines were filtered onto 0.2 micron filters and material extracted using the MoBio Water DNA extraction kit. The DNA was analysed by Research and Testing Laboratories Inc. (Lubbock, Texas, USA) via 454 pyrosequencing.

The bacteria were analysed using primers set 10F-519R, which targets 16S rRNA genes. 16S rRNA genes associated with chloroplast and mitochondria are included in this dataset but represent a minority of sequences in most samples. Eukaryotes were analysed using primers set 550F-1055R, which targets 18S rRNA genes. The 454 pyrosequencing analysis with the Titanium GS FLX+ kit used generates on average 3000 reads incorporating custom pyrotags for later stages of the data analysis.

The specific steps used for subsequent data analysis are described in the attached PDF file (Data_Analysis_Methodology.PDF). This output was further refined by first determining consensus sequences at the 98% similarity level using Weizhong Li’s online software site CD-HIT (weizhongli-lab.org/cd-hit/) Reference: Niu B, Fu L, Sun S, Li W. 2010. Artificial and natural duplicates in pyrosequencing reads of metagenomic data.

BMC Bioinformatics 1:187 doi:10.1186/1471-2105-11-187. The consensus sequences were then checked for errors, manually curated, and aligned against closest matching sequences obtained from the NCBI database (www.ncbi.nlm.nih.gov) to finally obtained a list of consensus operational taxonomic entities and the number of reads obtained for each samples analysed. File: SIPEXII_DNA_Sample_information.xlsx provides sampling and analysis information for the detailed results in the other two files File: SCIPEXII__sea_ice_bacteria_OTUs.xlsx contains information on the number of 16S rRNA reads in bacteria Phylum/Class and OTUs File: SCIPEXII_sea_ice_brines_eukaryote_community_OTU_data.xlsx contains information on the number of 16S rRNA reads in eukaryotic microbes: Phylum/Order/Closest taxon and OTUs