show Abstracthide AbstractThe genome data here presented, is the result of 1.5 years of enrichment of a pre-existing enrichment culture published by Ettwig et al. 2010, where sediment from the Ooij polder in the Netherlands resulted in a new anaerobic methane oxidizer: “Candidatus Methylomirabilis oxyfera”. We have derived a second enrichment, and both were maintained under nitrite feed and methane as electron acceptor only. In addition we have supplemented the trace element solution with Cerium, after preliminary indications that methanol dehydrogenase (MDH) is a lanthanide dependent enzyme, rather than a Calcium-dependent as previously thought. The sequencing of this enrichment resulted in the bin of a new species of the genera Methylomirabilis within the NC10, however the 16S gene is 97% identical which qualifies this organisms as a new species.