Genome properties The genome statistics are provided in Table 3 and Figure 3. The genome consists of a 4,215,469 bp long chromosome (cArct_4215) and five high throughput screening extrachromosomal elements with 279,891 bp, 228,923 bp, 203,324 bp, 92,209 bp and 29,416bp length, respectively (pArct_A280 – pArct_E29), with a G+C content of 59.3% (Table 3 and Figure 3). The identification of the scaffolds as chromosome and as extrachromosomal elements is explained below. Of the 4,909 genes predicted, 4,828 were protein-coding genes, and 81 RNAs; 102 pseudogenes were also identified. Although the five 16S rRNA gene copies in the genome were identical, one of the adjacent 16S-23S rRNA gene internal transcribed spacer (ITS) differs in five nucleotides from the four other copies. The majority of the protein-coding genes (77.

7%) were assigned a putative function while the remaining ones were annotated as hypothetical proteins. The distribution of genes into COGs functional categories is presented in Table 4. Table 3 Genome Statistics Figure 3a Graphical map of the Phaeobacter arcticus DSM 23566T chromosome cArct_4215. From bottom to the top: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, other RNAs black), … Table 4 Number of genes associated with the general COG functional categories Figure 3b Graphical map of the Phaeobacter arcticus DSM 23566T extrachromosomal element pArct_A280. From outside to the center: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, .

.. Figure 3c Graphical map of the Phaeobacter arcticus DSM 23566T extrachromosomal element pArct_B229. From outside to the center: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, … Figure 3d Graphical map of the Phaeobacter arcticus DSM 23566T extrachromosomal element pArct_C203. From bottom to the top: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, … Figure 3e Graphical map of the Phaeobacter arcticus DSM 23566T extrachromosomal element Cilengitide pArct_D92. From bottom to the top: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, other … Figure 3f Graphical map of the Phaeobacter arcticus DSM 23566T extrachromosomal element pArct_E29. From outside to the center: Genes on forward strand (color by COG categories), Genes on reverse strand (color by COG categories), RNA genes (tRNAs green, rRNAs red, …