title: Production of thermo-alkali-stable laccase and xylanase by co-culturing of Bacillus sp. and B. halodurans for biobleaching of kraft pulp and deinking of waste paper.
abstract: To reduce pollution and cost of treatment for fresh and recycled paper, co-production of xylanase and laccase was carried out in the same production medium using two compatible species of Bacillus. These co-produced enzymes were used for deinking of old newsprint (ONP) and biobleaching of eucalyptus Kraft pulp. Solid-state co-cultivation of Bacillus sp. and B. halodurans FNP135 was optimized statistically by response surface methodology for the co-production of xylanase (X) and laccase (L). A significant increase in production of xylanase (2.1-fold, 1,685 IU/g) and laccase (2.04-fold, 2,270 nkat/g) was observed under optimized conditions viz. pH (10.5), inoculum size (10 + 10 %) and moisture:substrate ratio (0.8:1). Both the enzymes showed identical temperature and pH optima of 70 °C and 9, respectively, and were used for deinking of ONP pulp and biobleaching of kraft pulp. In case of ONP pulp deinking, the XL treatment increased brightness (11.8 %), freeness (17.8 %), breaking length (34.8 %), burst factor (2.77 %) and tear factor (2.4 %). In case of kraft pulp biobleaching, XL treatment showed a significant increase in brightness (13 %), whiteness (106.15 %) breaking length (49 %), burst factor (6.9 %), tear factor (23 %), and viscosity (11.68 %) and reduction in kappa number (15 %) after alkali extraction and peroxide stage. This enhancement of pulp properties revealed a synergistic effect of xylanase and laccase produced in one setup.
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh, 160014, India.
authors.forename: Vijaya
authors.initials: V
authors.lastname: Gupta
authors.forename: Shruti
authors.initials: S
authors.lastname: Garg
authors.forename: Neena
authors.initials: N
authors.lastname: Capalash
authors.forename: Naveen
authors.initials: N
authors.lastname: Gupta
authors.forename: Prince
authors.initials: P
authors.lastname: Sharma
mesh_terms: D000468:Alkalies; D001407:Bacillus / Q000201:enzymology*; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis*; D005052:Eucalyptus / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology; D042845:Laccase / Q000096:biosynthesis*; D008031:Lignin / Q000737:chemistry; D010209:Paper; D019800:Phenol / Q000737:chemistry; D059027:Recycling; D013662:Tea; D013696:Temperature; D014908:Triticum
chemical_list: D000468:Alkalies; D013662:Tea; D019800:Phenol; D008031:Lignin; D042845:Laccase; D043364:Endo-1,4-beta Xylanases