Paper pulp modification and deinking efficiency of cellulase-xylanase complex from Escherichia coli SD5

Ligno-cellulosic enzymes like cellulase and xylanase have potential for modification of paper pulp characteristics. A low molecular weight cellulase - xylanase complex (14 KDa) was co-produced using Escherichia coli SD5. Co-existence of these enzymes was found to be advantageous in paper pulp modification and in deinking applications. The cellulase and xylanase exhibited specific activities of 51.95 and 24.64 U/mg protein of respectively. Defibrillations, crack formation and changes in functional groups was evident from the SEM and FT-IR analysis of paper pulp following the enzyme treatment. The enzyme facilitated a better reduction of Kappa number and Hexenuronic acid (Hex A) compared to earlier studies. A Δ brightness of approximately 10% were achieved in case of both cellulase and xylanase for different treatment time. The tear strength of recycled paper was also found to increase after the enzymatic treatment. This is the first report on the application of a un-engineered E. coli isolate co-producing cellulase-xylanase for paper industrial application.