Draft Genome Sequence of Paenisporosarcina sp. Strain TG-14, a Psychrophilic Bacterium Isolated from Sediment-Laden Stratified Basal Ice from Taylor Glacier, McMurdo Dry Valleys, Antarctica

GENOME ANNOUNCEMENT

Paenisporosarcina sp. TG-14 was isolated from sediment-laden stratified basal ice from Taylor Glacier, McMurdo Dry Valleys, Antarctica. The environments of Taylor Glacier in Antarctica include constant low temperatures, physical isolation, and permanent darkness (10). Glacial environments were thought to be virtually abiotic for many years (15). However, recent studies have shown that glaciers are one of the biotic environments containing many psychrophilic organisms (7, 13). Although various studies have been conducted to isolate microorganisms from glacial environments, there is little information on the survival mechanisms, such as cold adaptation, overcoming of low membrane fluidity, and activity of transcriptional/translational enzymes and protein folding (3, 4). We have sequenced the genome of Paenisporosarcina sp. TG-14 to study cold adaptation and mechanisms in an extreme environment.

Taylor Glacier ice was collected from Antarctica in November 2007. Individual bacterial colonies were isolated from agar-solidified medium (Difco R2A agar) that was directly inoculated with meltwater from sediment-laden stratified basal ice. Paenisporosarcina sp. TG-14 is a Gram-positive and rod-shaped bacterium. Based on its 16S rRNA sequencing, Paenisporosarcina antarctica N-05(EF154512) was the most closely related cultured representative in the EzTaxon database (http://eztaxon-e.ezbiocloud.net/). Similarity between the 16S rRNA gene of Paenisporosarcina sp. TG-14 and that of Paenisporosarcina antarctica N-05 was 99.71%. DNA was isolated from Paenisporosarcina sp. TG-14 using a genomic DNA (gDNA) extraction kit (Epicentre) and analyzed using the Illumina HiSeq 2000 (San Diego, CA) (2) with a 300-bp paired-end library (69,887,813 reads). The Illumina HiSeq 2000 sequencing achieved about 1,844-fold coverage. The reads generated by Illumina HiSeq 2000 were assembled using CLC Genomics Workbench v5.0 (CLC bio), and the resulting contigs were curated by CodonCode Aligner v3.7 (CodonCode Co.). Gene prediction and annotation were carried out using Glimmer3, tRNA-Scan, EzTaxon-e with hidden Markov model searching, NCBI Reference Sequences, and several open databases (5, 6, 9, 11, 12, 14, 16). The draft genome of Paenisporosarcina sp. TG-14 (about 3,826,160 bp) contains 135 contigs (the N₅₀ contig size was approximately 60,912 kb). The G+C content was 37%. A total of 3,747 protein-encoding genes and 56 tRNA genes were annotated in the draft genome, and 5 rRNA operons were predicted based on the sequence coverage value. Approximately 82.4% of nucleotides were predicted as protein-coding regions, and 1,721 (45.2%) of the protein-coding sequences were annotated with known proteins. Comparison of genome sequences available from the rapid annotations using subsystems technology (RAST) server (1) shows that Bacillus sp. B-14905 (genome identification [ID], 101,031.3; score, 542) and Lysinibacillus sphaericus C3-41 (genome ID, 444,177.5; score, 529) are the closest neighbors of strain TG-14. Paenisporosarcina sp. TG-14 may possess antifreeze protein (AFP), which is involved in the cold adaptation mechanism. AFPs bind to ice crystals to suppress their growth so that freeze-tolerant organisms can survive at low temperatures (8). The genome sequence of Paenisporosarcina sp. TG-14 will provide significant genetic information to identify the genes linked to its specific evolutionary mechanisms for cold adaptation.