Purification and characterization of thermostable cellulase from consortium XM70 in terrestrial hot spring with sugarcane bagasse

Abstract

Purpose: To better understand the sugarcane bagasse (SCB) degradation process and obtain thermostable cellulase from terrestrial hot spring. Methods: Molecular community structure of the newly selected thermophilic bacterial consortium XM70 was determined using the method of the full-length 16S rRNA library-based analysis. The thermostable CMCase was purified with ion-exchange and gel filtration chromatography. Results: Sequence-based identification of species belonging to the genera, Geobacillus, Desulfotomaculum, Bacillus, Exiguobacterium, Paenibacillus and Enterobacter were identified. The maximal activities of carboxymethyl cellulase (CMCase), filter paper cellulase and β-glucosidase of the consortium XM70 were obtained after incubation at 60 °C and pH 6.0 (4 days), 80 °C and pH 7.0 (2 days) and 70 °C and pH 8.0 (4 days), respectively. The yield of reducing sugars in the culture broth achieved 0.11 g.g -1 dry SCB. An extracellular CMCase from consortium XM70 (XM70-CMCase) was purified 7.9-fold to apparent homogeneity with a recovery of 65.41 % and its molecular mass was about 31.0 kDa. Maximum CMCase activity of the purified XM70-CMCase was 3.77 U/mg at 70 °C and pH 7.0. CMCase activity maintained about its maximal value of 70 % after incubation at 80 °C for 60 min. Conclusion: Due to its high temperature stability, the purified XM70-CMCase may be useful for industrial application such as biofuel, animal feed industry, paper industry and clarification of fruit juices.