S lineage: the tiny filamentous brown alga Ectocarpus siliculosus (Charrier et al., 2008). This species was selected since it is closely related Ralfinamide Cancer towards the kelp-forming Laminariales, both groups possessing separated approximately one hundred million years ago (Silberfeld et al., 2010), and because it features a little genome, is easy to cultivate inside the laboratory, and possesses a quick life cycle which tends to make it suitable for genetic studies (Peters et al., 2004). These days, numerous tools have been established for this model, comprising its comprehensive genome sequence (Cock et al., 2010), genetic maps (Heesch et al., 2010), a mutant collection (Le Bail et al., 2011), transcriptomics (Le Bail et al., 2008; Dittami et al., 2009), and proteomics (Contreras et al., 2008). But, as ofwww.frontiersin.orgJuly 2014 | Volume five | Write-up 241 |Dittami et al.The “Ca. Phaeomarinobacter ectocarpi” genometoday, very tiny knowledge is available about the bacteria associated with this model program. Indeed, the only published information presently accessible on the influence of bacteria on Ectocarpus are studies carried out by M. Peders over 40 years ago (Peders , 1968, 1969, 1973). They showed that antibiotic-treated Ectocarpus fasciculatus, a sister species of E. siliculosus, which separated from the latter roughly 19 million years ago (Dittami et al., 2012), exhibited poor development and abnormal morphology, but that these effects might be reversed by the addition of cytokinins. Here we address the query of algal-bacterial associations inside the brown algal model Ectocarpus by analyzing the nearly full genome of a bacterium that was sequenced collectively with E. siliculosus. We show that this bacterium belongs to a new, mostly marine, genus closely related to Rhizobiales–an order comprising various soil bacteria that enter mutualistic relationships with plant roots. In spite of the fact that we have not been able to Adhesion Proteins Inhibitors Reagents culture this bacterium, for which we propose the name “Candidatus Phaeomarinobacter ectocarpi,” we found it to be often linked with brown algae, and also the evaluation of its genome, at the same time because the reconstruction of its metabolic network, enabled us to kind several hypotheses concerning the biology of this organism along with the interactions it might have with Ectocarpus. This sort of knowledge contributes to our fundamental understanding on the functioning of algal-bacterial holobionts, but may perhaps also prove helpful within the context of the sustainable utilization of algae as a organic resource.genome of Zobellia galactanivorans DsijT (accession FP476056), a genome of a marine bacterium for which all protein sequences have been subject to professional annotation. All of our manual annotations had been incorporated both in to the final genome release and also the draft metabolic network. The resulting curated metabolic network is available in Pathway Tools by way of the SRI Registry of PathwayGenome Databases and around the public Pathway Tools server of the Station Biologique de Roscoff (http:pwt.sb-roscoff. fr). The manually annotated “Ca. P. ectocarpi” genome was deposited at the European Nucleotide Archive (ENA) below the accession number HG966617.COMPARISON AND COMPLEMENTARITY OF “CA. P. ECTOCARPI” AND E. SILICULOSUS METABOLIC NETWORKSMATERIALS AND METHODSGENOME SEQUENCE, ANNOTATION, AND METABOLIC NETWORK RECONSTRUCTIONThe genome sequence of “Ca. P. ectocarpi” was obtained within the course in the E. siliculosus genome project (Cock et al., 2010). It was assembled collectively with the algal genome and was available from.