“…During a systematic search of a Mediterranean DCM metagenomic fosmid library (Ghai et al, 2010) for rRNA genes, we identified four fosmids (6.2 to 36 to kb in size) containing rRNA sequences classified as MGII, two of them containing 16S rRNA and the other two 23S rRNA genes (Supplementary Figure 1). Interestingly, they had an atypical low GC content (34-40%) compared with the 52% of the assembled MG2-GG3 genome (Iverson et al, 2012) or the MGII fosmids previously described (DeLong et al, 1999;Moreira et al, 2004;Frigaard et al, 2006;Martin-Cuadrado et al, 2008;Rich et al, 2008;Ghai et al, 2010;Deschamps et al, 2014). MGII have the two rRNA genes separated in the genome (Moreira et al, 2004;Martin-Cuadrado et al, 2008), a feature observed also in the Thermoplasmatales and in A. boonei (Ruepp et al, 2000;Moreira et al, 2004).…”