Production of thermostable pectinase and xylanase for their potential application in bleaching of kraft pulp

• Published in: Journal of industrial microbiology & biotechnology Vol. 34; no. 12; pp. 763 - 770
• Main Authors: Ahlawat, Sonia, Battan, Bindu, Dhiman, Saurabh Sudha, Sharma, Jitender, Mandhan, Rishi Pal
• Format: Journal Article
• Language: English
• Published: Heidelberg Berlin/Heidelberg : Springer-Verlag 01.12.2007; Springer; Oxford University Press
• Subjects: Bacillus - enzymology; Bacillus - growth & development; Bacillus pumilus; Bacillus subtilis; biobleaching; Biological and medical sciences; Biotechnology; Bleaching; Cellulose - metabolism; Chlorine; Crop residues; endo-1,4-beta-xylanase; Enzymes; Fermentation; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Industrial Microbiology - methods; kraft pulp; papermaking; plant residues; polygalacturonase; Polygalacturonase - metabolism; Pulp & paper mills; pulp and paper industry; pulp and paper products; pulp and paper technology; soil bacteria; submerged fermentation; Temperature; thermal stability; Triticum aestivum; Wheat bran; Xylosidases - metabolism; Yeasts; Cellulase-free; Enzyme; Paper pulp; Pectinase; Endo-1,4-β-xylanase; Polygalacturonase; Biobleaching; Thermal stability; Glycosylases; Xylanase; Bleaching; Cellulase; Glycosidases; Production; Hydrolases; Thermostable; Xylan endo-1,3-β-xylosidase; Application
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1007/s10295-007-0251-3

A very high level of alkalophilic and thermostable pectinase and xylanase has been produced from newly isolated strains of Bacillus subtilis and Bacillus pumilus respectively. Enzyme production for pectinase was carried out under SSF using combinations of cheap agricultural residues while xylanase was produced under submerged fermentation using wheat bran as substrate to minimize the cost of production of these enzymes Among the various substrates tested, the highest yield of pectinase production was observed by using combination of WB + CW (6592 U/g of dry substrate) supplemented with 4% yeast extract when incubated at 37 °C for 72 h using deionized water of pH 7.0 as moistening agent. The biobleaching effect of these cellulase free enzymes on kraft pulp was determined. Both xylanase and pectinase showed stability over a broad range of pH from 6 to 10 and temperature from 55 to 70 °C. The bleaching efficiency of the pectinase and xylanase on kraft pulp was maximum after 150 min at 60 °C using enzyme dosage of 5 IU/ml of each enzyme at 10% pulp consistency with about 16% reduction in kappa number and 84% reduction in permanganate number. Enzyme treated pulp when subjected to CDED₁D₂ steps, 25% reduction in chlorine consumption and upto 19% reduction in consumption of chlorine dioxide was observed for obtaining the same %ISO brightness. Also an increase of 22 and 84% in whiteness and fluorescence respectively and a decrease of approximately 19% in the yellowness of the biotreated pulp were observed by pretreatment of the pulp with our enzymatic mixture.