Enhancing the Cellulose-Degrading Activity of Cellulolytic Bacteria CTL-6 ( Clostridium thermocellum ) by Co-Culture with Non-cellulolytic Bacteria W2-10 ( Geobacillus sp.)

The effect of a non-cellulolytic bacterium W2-10 ( Geobacillus sp.) on the cellulose-degrading activity of a cellulolytic bacterium CTL-6 ( Clostridium thermocellum ) was determined using cellulose materials (paper and straw) in peptone cellulose solution (PCS) medium under aerobic conditions. The results indicated that in the co-culture, addition of W2-10 resulted in a balanced medium pH, and may provide the required anaerobic environment for CTL-6. Overall, addition of W2-10 was beneficial to CTL-6 growth in the adverse environment of the PCS medium. In co-culture with W2-10, the CTL-6 cellulose degradation efficiency of filter paper and alkaline-treated wheat straw significantly increased up to 72.45 and 37.79 %, respectively. The CMCase activity and biomass of CTL-6 also increased from 0.23 U ml −1 and 45.1 μg ml −1 (DNA content) up to 0.47 U ml −1 and 112.2 μg ml −1 , respectively. In addition, co-culture resulted in accumulation of acetate and propionate up to 4.26 and 2.76 mg ml −1 . This was a respective increase of 2.58 and 4.45 times, in comparison to the monoculture with CTL-6.