Old newspaper (ONP) wastes were used as the sole carbon source for growing Bacillus subtilis. Avicelase and carboxymethylcellulase (CMCase) cellulolytic enzymes were estimated in culture filtrate. A maximum yield of 193.4 and 121.4 % was recorded for Avicelase and CMCase respectively, comparing with 100 % yield in case of control. Avicelase optimum enzyme activity (2.822 U/ml) was recorded at 50°C, however, CMCase optimum activity (3.971 U/ml) was at 30°C. In a similar way, the optimal enzymes activities pH profile was identical and showed the maximal activity up to (2.500 and 4.364 U/ml) at pH value of 6.0 for Avicelase and CMCase, respectively. Bacillus subtilis CMCase has more activity at optimal temperature and pH than Avicelase. The enzymatic de-inking was indicated by the brightness of the sheets due to the remove of the ink particles effectively and prevents redeposition onto the fiber surfaces.
Key words: Biological de-inking, Bacillus subtilis, Avicelase, Carboxymethylcellulase.
|
