STATISTICAL APPROACH FOR PECTINASE PRODUCTION BY Bacillus firmus SDB9 AND EVALUATION OF PECTINO- XYLANOLYTIC ENZYMES FOR PRETREATMENT OF KRAFT PULP

The present study originated with the concomitant production of 1.94 IU. mL(-1) of pectinase, 0.34 IU. mL(-1) xylanase and 0.086 IU. mL(-1) cellulase from a newly isolated Bacillus firmus SDB9 in pectin salt media. Plackett-Burman Design (PBD) and Box-Behnken design (BBD) were used for optimization of mass production of pectinase using agro-residues. Statistical optimization of medium enhances the pectinase production to 17.55 IU. mL(-1), 17.7% higher activity than that of unoptimized medium. The optimal pectinase activity was found at pH 8.5 and 45 degrees C temperature. The enzyme was alkali-stable over a range of pH 7.0 to 10.0 for 1 h and thermostable at 35 to 70 degrees C for 1h. Out of 12 tested metal cations at 1mM concentration, the enzyme was found to be hindered by the presence of three cations, whereas four cations were reported to augment, and the rest marginally subdued the activity. Pretreatment with 15 IU pectinase and 2.7 IU xylanase per gram of OD pulp reduce kappa number by 7.9%. After bleaching sequence D0-Ep-D1, the increment in pulp brightness was 2.7% with acceptable whiteness level. Pretreatment also led to a reduction in ClO2 consumption by 15% with superior brightness level. The 0.83% increase in pulp viscosity along with 3.2% gain in double fold number indicated the maintenance of relative cellulose content and strength of paper. Minor variations in burst index, tensile index and tear index reflected the conserved properties of the treated pulp. Synergistic application of mixed enzymes preparation produced from raw agro-residue headed by pectinase in preference to xylanase is first time set forth in the present study to help in cost economization and propel the pulp and paper industries towards environmental friendly future.