The clones of the top cluster of the tree were mainly classified to the genus Acetivibrio and were closely related to C. thermocellum and C. straminisolvens (Fig. 3). It is known that C. thermocellum is a cellulosome-producing bacterium. It will be important to determine whether the strains in the community isolated can produce a cellulosome. To our knowledge, cellulosome-producing bacteria have never been found in any marine environment. A theory explaining how the thermophiles accumulated in the cold

ocean concludes that the thermophiles are produced by seabed fluid flow from warm subsurface petroleum reservoir and ocean crust ecosystems (Hubert et al., 2009). These authors also found that all these thermophilic bacteria are spore-forming Firmicutes species. The diversity of cellulases of GHF48 was explored as a functional gene indicative selleck of truly cellulolytic bacteria (Izquierdo et al., GSK2118436 ic50 2010). GHF48 gene is known for its ability to enhance cellulose solubilization in synergistic interactions with family 9 glycosyl hydrolases and mostly single copies in the genomes of cellulolytic microbes (Irwin et al., 2000; Berger et al., 2007). The cloned GHF48 sequences were blasted against the NCBI database. The results showed that these

sequences shared the closest similarities to the uncultured bacterial clone from the thermophilic biocompost enrichments, Clostridium lentocellum CHIR-99021 chemical structure and C. straminisolvens (Izquierdo et al., 2010). The diversity of GHF48 was low, which is in accordance with our result that most of the 16S rRNA of the cellulolytic bacteria were the most closely related to C. thermocellum. The phylogenetic tree of these sequences and their closest related strains from the GenBank were constructed (Fig. 4). The GHF48 clones were classified

to two general branches (Fig. 4). All GHF48 sequences belonged to Clostridia. The upper branch contained clones G2, G7 and G19 (with a total proportion of 72%). They were most similar to the uncultured bacterium clone CO6-G1 and CO6-G35 GHF48 gene, and C. straminisolvens strain CSK1 GHF48 gene, respectively, with only 70% amino acid sequence similarity to Caldicellulosiruptor bescii GHF48 protein. The lower branch contained clones G6, G11 and G22, accounting for 28% of the clone library, with 71% amino acid sequence similarity to the GHF48 identified in Herpetosiphon aurantiacus. This work was supported by grants from the National Basic Research Program of China (No. 2011CB707404) and National Key Technology R&D Research Program (2011BAD22B02-01). “
“Andean wetlands are characterized by their extreme environmental conditions such as high UV radiation, elevated heavy metal content and salinity.