Several phylotypes were affiliated with unclassified environmental clone groups, UBSedI to VI and UBMnI and II, as defined in the present study (Fig. S2e). Phylotypes in the Gammaproteobacteria were abundant in the clone libraries from the Mn crust and sediment samples (24.0% and 23.5% of the total

clone numbers, respectively; Fig. 3). These phylotypes were related to not yet cultivated environmental clones recovered from seafloor basaltic rocks (Lysnes et al., 2004; Mason et al., PLX-4720 mouse 2007, 2008; Santelli et al., 2008) rather than cultured species (<95% similarity) (Fig. S2b). In contrast, phylotypes in the Alphaproteobacteria were abundant in the clone libraries from the seawater sample (44.3% of the total clone number). In particular, most of them were related to Candidatus Pelagibacter (SAR11 cluster, Rappéet al., 2002) and Sphingomonadales (Fig. S2c), groups from which members have often been recovered from deep-sea water of >1000 m water depth (García-Martínez & Rodríguez-Valera, 2000; Delong et al., 2006; Kato et al., 2009a, c). Comparative analysis showed that the microbial community composition of the Mn crust was different from those of the sediment and overlying seawater. The differences

among the three communities were supported by the UniFrac significance and P values (<0.01). To compare the microbial community composition, the shared phylotype numbers among the libraries from the crust, sediment FAD and seawater

samples were estimated selleck chemicals llc using sons. The Mn crust and sediment communities shared few or no phylotypes with the seawater community (Fig. 4). The Mn crust community contained a fraction of phylotypes recovered from the sediment sample (20% of the total phylotype richness estimates of the Mn crust; Fig. 4). Thus, 80% of the total phylotypes richness estimates of the Mn crust community were unique compared with the sediment communities. In fact, unique phylotypes of the Mn crust were observed in the phylogenetic trees (Fig. S2). Several phylotypes in MGI were shared between the Mn crust and sediment, but not between the Mn crust and seawater (Fig. S2a) as described above. Phylotypes related to the genus Nitrosospira in the Betaproteobacteria were unique in the Mn crust (Fig. S2b). Representative clone 953Mn48u has 97% similarity to the ammonia-oxidizing chemolithoautotrophic bacterium Nitrosospira multiformis (Watson et al., 1971). Phylotypes related to the family Ectothiorhodospiraceae in the Gammaproteobacteria were also unique in the library of the Mn crust (Fig. S2b). Representative clone 953Mn100u has 94% similarity to the arsenite-oxidizing chemolithoautotroph Alkalilimnicola ehrlichii (Hoeft et al.