<p><font size="3">At present there are 24 cyanobacteria for which a total genome sequence is available. 15 of these cyanobacteria come from the marine environment. These are six <em>Prochlorococcus</em><em>Synechococcus</em> strains, <em>Trichodesmium erythraeum</em> IMS101 and <em>Crocosphaera watsonii</em> [[WH8501. Several studies have demonstrated how these sequences could be used very successfully to infer important ecological and physiological characteristics of marine cyanobacteria. However, there are many more genome projects currently in progress, amongst those there are further <em>Prochlorococcus</em> and marine <em>Synechococcus</em> isolates, <em>Acaryochloris</em> and <em>Prochloron</em>, the N₂-fixing filamentous cyanobacteria <em>Nodularia spumigena</em>, <em>Lyngbya aestuarii</em> and <em>Lyngbya majuscula</em>, as well as bacteriophages infecting marine cyanobaceria. Thus, the growing body of genome information can also be tapped in a more general way to address global problems by applying a comparative approach. Some new and exciting examples of progress in this field are the identification of genes for regulatory RNAs, insights into the evolutionary origin of photosynthesis, or estimation of the contribution of horizontal gene transfer to the genomes that have been analyzed.<sup class="reference" id="_ref-Herrero_0">[10]</sup></font> strains, seven marine </p><p>&nbsp;<font size="4">[[Genome sequencing and genomics]]</font></p>