For example, it was reported that Caldicoprobacter oshimai was a xylanolytic, extremely thermophilic bacterium (Yokoyama et al., 2010). The OTU which showed the closest similarity with C. oshimai might also be a PI3K Inhibitor Library price xylanolytic bacterium, which would play an important role in lignocellulose degradation. Another example was one OTU which represented 4% of the clone library, and one strain from the OTU which had been isolated
as pure culture. This strain was named ASX2 and shared 90.4% 16S rRNA gene sequence identity with Desulfotomaculum halophilum SEBR 3139. ASX2 was able to hydrolyze CMC, as determined by formation of a clear zone on a Congo Red agar plate (data not shown). Beta-glucosidase was also found in strain ASX2. It is noteworthy that most of the clones represented by the clone library Bafetinib mouse shared 16S rRNA similarities lower than 90%, and all of them shared 16S rRNA similarities below 94%, which meant that they were novel at least at species level. One example was the isolation of strain ASX2 mentioned above. Another example was the isolated pure culture which shared 93% 16S rRNA sequence identity with Bacillus thermolactis. The general low 16S rRNA similarity might be attributable to the fact that the coastal marine environment was thought to be hypothermal, so thermophilic
bacteria were ignored. In our experiment, the selection pressure put on by thermophilic and anaerobic conditions and the limited carbon source eliminated bacterial species which were commonly found by traditional isolation methods under low temperature and aerobic conditions. The blast results
showed that the known strains most closely related to the sequenced clones were all from a terrigenous environment, for example Planifilum yunnanense isolated from a hot spring, Sporosalibacterium faouarense isolated from oil-contaminated Orotic acid soil, D. halophilum isolated from an oilfield brine and C. oshimai isolated from sheep feces (Tardy-Jacquenod et al., 1998; Zhang et al., 2007; Yokoyama et al., 2010; Rezgui et al., 2011). A few of them such as D. halophilum and S. faouarense were reported as moderately halophilic bacteria (Tardy-Jacquenod et al., 1998; Rezgui et al., 2011). As we know, the marine environment was of high salinity and there is a possibility that these bacteria from land had adapted to the marine saline conditions and at last settled down in the ocean. However, the isolation environment and the low 16S rRNA similarity might indicate the opposite possibility, which was that the evolution positions of our clones pre-dated the isolated terrigenous strains. Briefly, the halophilic and thermophilic properties of these bacteria are unexpected and provide an interesting area for future studies. The phylogenetic tree of these clones and their closest related strains from the GenBank were constructed through the NJ method (Fig. 3). As shown in Fig. 3, all of the clones formed separate branches from the known species.