In order to obtain the cellulolytic bacterial consortia, sediments from Great Basin hot springs (Nevada, USA) were sampled and enriched with cellulosic biomass as the sole carbon source. The bacterial composition of the resulting anaerobic ethanol-producing celluloytic bacterial consortium, named SV79, was analyzed. With methods of the full-length 16S rRNA librarybased analysis and denaturing gradient gel electrophoresis, 21 bacteria belonging to eight genera were detected from this consortium. Clones with closest relation to the genera Acetivibrio, Clostridium, Cellulosilyticum, Ruminococcus, and Sporomusa were predominant. The cellulase activities and ethanol productions of consortium SV79 using different agricultural residues (sugarcane bagasse and spent mushroom substrate) and energy crops (Spartina anglica, Miscanthus floridulus, and Pennisetum sinese Roxb) were studied. During cultivation, consortium SV79 produced the maximum filter paper activity (FPase, 9.41 U/ml), carboxymethylcellulase activity (CMCase, 6.35 U/ml), and xylanase activity (4.28 U/ml) with sugarcane bagasse, spent mushroom substrate, and S. anglica, respectively. The ethanol production using M. floridulus as substrate was up to 2.63 mM ethanol/g using gas chromatography analysis. It has high potential to be a new candidate for producing ethanol with cellulosic biomass under anoxic conditions in natural environments.

In the present study, a thermophilic anaerobic bacterial consortium YTY-70 that produced thermostable b-galactosidase was isolated from a hot spring in Yongtai (Fujian, China). Based on 16S rRNA sequences, we concluded that Caldicellulosiruptor was the predominant genus in the studied bacterial consortium. Subsequently, a thermostable b-galactosidase gene was cloned and expressed in Escherichia coli as a fusion protein with glutathione S-transferase. The recombinant enzyme exhibited a maximum activity at an optimum pH of 7.0 and an optimum temperature of 75 C. It had a high activity across a broad pH range (between pH 5.0 and pH 9.0) and high thermal stability at temperatures up to 90 C. The activity of the recombinant b-galactosidase was enhanced by TritonX-100, Tween-20 and 1 mmol/L 2-mercaptoethanol, while it was inhibited by ethylenediaminetetraacetic acid, sodium dodecyl sulphate, phenylmethylsulphonyl fluoride and 10 mmol/L 2-Me. The enzyme's catalytic function was enhanced by the following metal ions: Na C , K Fe 3C and Li C . The thermostable b-galactosidase might be a promising candidate for use in food industries, particularly for the dairy industry and biosynthesis of galacto-oligosaccharides, due to its high thermostability and broad pH range.

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