Characteristics of cellulase in cellulose-degrading bacterium strain Clostridium straminisolvens (CSK1)

Microbial degradation of biomass was considered as a clean and highly efficient approach to produce bioenergy, as it could mitigate the urgent demand for limited petroleum and natural gas. A thermophilic microbial consortium (MC1) was proved a high efficiency cellulose-degrading bacterial community in previous studies. A novel anaerobic, thermophilic, and cellulolytic bacterium (strain CSK1) was isolated from MC1. The cellulase activity characteristics of CSK1 were analyzed and evaluated by exploring new measuring conditions via the 3,5-dinitrosalicylic acid (DNS) spectrophotometry and the carboxymethyl cellulose (CMC) saccharogenic power method. The results indicated that the optimal measuring wavelength, reaction temperature, and pH value, were 530 nm, 60°C and 6.0, respectively. The ideal reaction time to achieve stable and significant measuring cellulase activity was about 10 min. Cellulase of CSK1 remained stable when the temperature was below 70°C, and the pH between 5.0 and 10.0, and its activity was quickly reduced when the temperature and pH exceeded such ranges. The cellulase activity of CSK1 reached the highest level on culturing day 8, and high correlations were found among cellulase activity variation, pH and CSK1 biomass change. Key words: Strain CSK1, cellulose degradation, composite microbial system microbial consortium (MC1), 3,5-dinitrosalicylic acid (DNS) spectrophotometry, enzyme activity.