A pollution reducing enzymatic deinking approach for recycling of mixed office waste paper.

The efficiency of xylano-pectinolytic enzymes, co-produced by a single microbial strain Bacillus pumilus, was analysed for the recycling of mixed office waste paper through deinking and compared with the alkaline chemical deinking method. Enzymes showed maximum deinking at pH 8.5, pulp consistency of 10%, xylanase-pectinase dose of 12 and 4 IU per gram pulp, respectively, after 120 min of deinking period, and temperature at 50 °C. A chemi-enzymatic approach was employed with xylano-pectinolytic enzymes and various concentrations of deinking chemicals, which showed that enzyme-treated mixed office waste pulp requires only 40% chemicals for deinking, in order to get the almost same level of various handsheets properties, as obtained by the chemical method with 100% chemicals. Similarly, the effluent load of BOD and COD contents was also decreased by 17.90 and 19.75%. This combinational approach of deinking significantly improved the various properties of the handsheets and resulted in gain of 7.5, 9.38, 6.33 and 11.65% in tear factor, burst factor, breaking length and viscosity of the handsheets, while the effective residual ink concentration analysis of deinked handsheets of mixed office waste paper showed deinking efficiency of 22.45%, which revealed the removal of ink particles during enzymatic deinking steps.

Fast flow rate processes for purification of alkaline xylanase isoforms from Bacillus pumilus AJK and their biochemical characterization for industrial application purposes.

This study shows the presence of five isozymic forms of alkaline xylanase from Bacillus pumilus using fast flow rate microfiltration, ultrafiltration, Q-sepharose, and phenyl sepharose chromatographic techniques. Polyacrylamide gel electrophoresis, high-performance liquid chromatography, and zymographic studies also revealed the purity of five isoforms of alkaline xylanases. Isoforms-X-I, X-III, and X-V exhibited optimum activity at pH 8.5, whereas X-II, X-IV showed maximum activity at pH 9. All isoforms were optimally active at temperature 55°C. Isoforms were found to be stable at pH 7-11, showed 92-100% residual activity after 3 hr, treatment time for most industrial applications. The isoforms retained nearly 80-86% residual activity after incubating at 45°C for 3 hr. Molecular weights of xylanase I-V, were 13.1, 15.3, 18.4, 20.1, and 21.0 kDa, respectively. Mg2+ ions were found to be potent activator for all isozymic forms. The Km and Vmax values of X-I, X-II, X-III, X-IV, and X-V were 6.71, 6.66, 7.14, 5.88, 6.25 mg/ml and 2,000, 1,695, 1,666.66, 1,428.57, and 1,408.45 IU/mg protein, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed the monomeric nature of all isoforms. The low-molecular masses, significantly enhanced activity in the presence of industrially suitable-low cost activator, better stability of all isoforms at pH 7-11 and at higher temperature, also presence of multiple forms of alkaline xylanase, makes this enzyme suitable for textile-paper industries. This is also the first report mentioning the purification of five isozymic forms of alkaline xylanase using fast flow rate techniques.

A novel and cost-effective methodology for enhanced production of industrially valuable alkaline xylano-pectinolytic enzymes cocktail in short solid-state fermentation cycle.

The aim of this study was to enhance the production of xylano-pectinolytic enzymes concurrently and also to reduce the fermentation period. In this study, the effect of agro-residues extract-based inoculum on yield and fermentation time of xylano-pectinolytic enzymes was studied. Microbial inoculum and fermentation media were supplemented with xylan and pectin polysaccharides derived from agro-based residues. Enzymes production parameters were optimized through two-stage statistical design approach. Under optimized conditions (temperature 37°C, pH 7.2, K2 HPO4 0.22%, MgSO4 0.1%, gram flour 5.6%, substrate: moisture ratio 1:2, inoculum size 20%, agro-based crude xylan in production media 0.45%, and agro-based crude xylan-pectin in inoculum 0.13%), nearly 28,255 ± 565 and 9,202 ± 193 IU of xylanase and pectinase, respectively, were obtained per gram of substrate in a time interval of 6 days only. The yield of both xylano-pectinolytic enzymes was enhanced along with a reduction of nearly 24 h in fermentation time in comparison with control, using polysaccharides extracted from agro-residues. The activity of different types of pectinase enzymes such as exo-polymethylgalacturonase (exo-PMG), endo-PMG, exo-polygalacturonase (exo-PG), endo-PG, pectin lyase, pectate lyase, and pectin esterase was obtained as 1,601, 12.13, 5637, 24.86, 118.62, 124.32, and 12.56 IU/g, respectively, and was nearly twofold higher than obtained for all seven types in control samples. This is the first report mentioning the methodology for enhanced production of xylano-pectinolytic enzymes in short solid-state fermentation cycle using agro-residues extract-based inoculum and production media.